Fix CI and bump the msrv of OTLP to 1.71.1

[utpilla]

Changes

• CI checks are failing
  • test workflow Needs to conform to the new code analysis rules of using Self instead of the type name
  • msrv workflow OTLP exporter and proto project have to use a newer version of rustc

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 78.9%. Comparing base (d652dc8) to head (deeb941).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #2140     +/-   ##
=======================================
- Coverage   79.0%   78.9%   -0.1%     
=======================================
  Files        121     121             
  Lines      20791   20780     -11     
=======================================
- Hits       16426   16416     -10     
+ Misses      4365    4364      -1     

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[lalitb]

If the CI is failing only for the msrv build, and not otherwise, we can do the msrv patch for prost instead of bumping rustc. That would be non breaking change.