Fix some deprecated api calls and clippy reports

[funArash]

Fixes #
Design discussion issue (if applicable) #

Changes

Please provide a brief description of the changes here.

Merge requirement checklist

• CONTRIBUTING guidelines followed
• Unit tests added/updated (if applicable)
• Appropriate CHANGELOG.md files updated for non-trivial, user-facing changes
• Changes in public API reviewed (if applicable)

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: funArash / name: Arash Bannazadeh-Mahani (1895ea0, 11698bb, ac64f19, 619d80e, 37be9ec)

[lalitb]

Thanks

[lalitb]

Can you also remove the exclusion of this project from Cargo.toml, so the build can be verified.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 53.3%. Comparing base (56a6f45) to head (ac64f19).
Report is 8 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main     #74     +/-   ##
=======================================
+ Coverage   52.3%   53.3%   +1.0%     
=======================================
  Files         38      38             
  Lines       4967    5026     +59     
=======================================
+ Hits        2598    2680     +82     
+ Misses      2369    2346     -23     

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[lalitb]

@funArash - There are some errors in CI build for Datadog if you can fix in this PR. Thanks.

 Documenting opentelemetry-datadog v0.10.0 (/home/runner/work/opentelemetry-rust-contrib/opentelemetry-rust-contrib/opentelemetry-datadog)
error: unexpected `cfg` condition value: `surf-client`
   --> opentelemetry-datadog/src/exporter/mod.rs:162:21
    |
162 |                 not(feature = "surf-client"),
    |                     ^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `feature` are: `agent-sampling`, `reqwest`, `reqwest-blocking-client`, `reqwest-client`, and `surf`
    = help: consider adding `surf-client` as a feature in `Cargo.toml`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration
    = note: `-D unexpected-cfgs` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(unexpected_cfgs)]`

error: unexpected `cfg` condition value: `surf-client`
   --> opentelemetry-datadog/src/exporter/mod.rs:168:17
    |
168 |                 feature = "surf-client"
    |                 ^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `feature` are: `agent-sampling`, `reqwest`, `reqwest-blocking-client`, `reqwest-client`, and `surf`
    = help: consider adding `surf-client` as a feature in `Cargo.toml`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

error: unexpected `cfg` condition value: `surf-client`
   --> opentelemetry-datadog/src/exporter/mod.rs:172:21
    |
172 |                 not(feature = "surf-client"),
    |                     ^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `feature` are: `agent-sampling`, `reqwest`, `reqwest-blocking-client`, `reqwest-client`, and `surf`
    = help: consider adding `surf-client` as a feature in `Cargo.toml`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

error: could not document `opentelemetry-datadog`

[funArash]

@funArash - There are some errors in CI build for Datadog if you can fix in this PR. Thanks.

 Documenting opentelemetry-datadog v0.10.0 (/home/runner/work/opentelemetry-rust-contrib/opentelemetry-rust-contrib/opentelemetry-datadog)
error: unexpected `cfg` condition value: `surf-client`
   --> opentelemetry-datadog/src/exporter/mod.rs:162:21
    |
162 |                 not(feature = "surf-client"),
    |                     ^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `feature` are: `agent-sampling`, `reqwest`, `reqwest-blocking-client`, `reqwest-client`, and `surf`
    = help: consider adding `surf-client` as a feature in `Cargo.toml`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration
    = note: `-D unexpected-cfgs` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(unexpected_cfgs)]`

error: unexpected `cfg` condition value: `surf-client`
   --> opentelemetry-datadog/src/exporter/mod.rs:168:17
    |
168 |                 feature = "surf-client"
    |                 ^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `feature` are: `agent-sampling`, `reqwest`, `reqwest-blocking-client`, `reqwest-client`, and `surf`
    = help: consider adding `surf-client` as a feature in `Cargo.toml`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

error: unexpected `cfg` condition value: `surf-client`
   --> opentelemetry-datadog/src/exporter/mod.rs:172:21
    |
172 |                 not(feature = "surf-client"),
    |                     ^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `feature` are: `agent-sampling`, `reqwest`, `reqwest-blocking-client`, `reqwest-client`, and `surf`
    = help: consider adding `surf-client` as a feature in `Cargo.toml`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

error: could not document `opentelemetry-datadog`

I cannot repo the errors locally.. am I missing something?

export CARGO_INCREMENTAL=0    
export RUSTDOCFLAGS=-Dwarnings

cargo doc --all-features --no-deps

[funArash]

found it.. cargo +nightly doc --all-features --no-deps reproed the errors