Remove Rust version from workspace

[duncanpharvey]

What does this PR do?

• Remove Rust version from workspace
• Add version 0.1.0 for dogstatsd crate

Motivation

Failing tests in libdatadog due to forced Rust version:

error: rustc 1.78.0 is not supported by the following package:
  dogstatsd@0.0.0 requires rustc 1.85
Either upgrade rustc or select compatible dependency versions with
`cargo update <name>@<current-ver> --precise <compatible-ver>`
where `<compatible-ver>` is the latest version supporting rustc 1.78.0

Also we won't be maintaining the crate version for now but it looked odd to have version 0.0.0 in the Cargo lock file. So 0.1.0 will be the version for the time being.

Additional Notes

Related PR in libdatadog: DataDog/libdatadog#973

Describe how to test/QA your changes