Add cloud_run_job to MonitoredResource

[fiadliel]

Fixes #100

Changes

Adds MonitoredResource::CloudRunJob which adds the appropriate labels for the cloud_run_job monitored resource type.

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)

[lalitb]

LGTM. Thanks for the PR.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 15 lines in your changes missing coverage. Please review.

Project coverage is 56.2%. Comparing base (56a6f45) to head (bef4d46).
Report is 27 commits behind head on main.

Files with missing lines	Patch %	Lines
opentelemetry-stackdriver/src/lib.rs	0.0%	15 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #101     +/-   ##
=======================================
+ Coverage   52.3%   56.2%   +3.9%     
=======================================
  Files         38      39      +1     
  Lines       4967    5461    +494     
=======================================
+ Hits        2598    3074    +476     
- Misses      2369    2387     +18     

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