chore: Upgrade opentelemetry-prometheus to 0.29

[BSteffaniak]

Changes

Upgrade the dependencies to the latest 0.29 version.

Not sure if you're still supporting this crate, but I figured this update is still simple enough.
 

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)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.8%. Comparing base (c5d5a1c) to head (7cd07b0).
Report is 1 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #2851   +/-   ##
=====================================
  Coverage   80.8%   80.8%           
=====================================
  Files        124     124           
  Lines      23682   23682           
=====================================
+ Hits       19137   19138    +1     
+ Misses      4545    4544    -1     

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[cijothomas]

https://github.com/open-telemetry/opentelemetry-rust/blob/main/opentelemetry-prometheus/src/lib.rs#L4-L8
Merging and releasing 0.29. As indicated in the doc, this will be the last release.