update msrv check, and bump opentelemetry-proto to v1.70.0

[lalitb]

Changes

• Update msrv for opentelemetry-proto to v1.70.0
• Enable msrv check for opentelemetry-proto and opentelemetry-otlp
• Modified the scripts/msrv.sh to be version agnostic. The package and version mapping is maintained in ./scripts/msrv_config.json.

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 74.5%. Comparing base (f1cdaca) to head (21f7264).

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #1864   +/-   ##
=====================================
  Coverage   74.5%   74.5%           
=====================================
  Files        122     122           
  Lines      19859   19859           
=====================================
  Hits       14808   14808           
  Misses      5051    5051           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[lalitb]

will reopen after fix.
Fixed now