fix(build): pin checkout actions for web build to 3.0.2

[pichlermarc]

Which problem is this PR solving?

This PR pins actions/checkout to v3.0.2 in the web builds, as v3.1.0 broke our pipeline.

Our pipeline uses the circleci/node:16-browsers image, which sets the default user to a non-root circleci user. This is an unsupported path according to GitHub Actions documentation. It causes files to be not writable, as they are owned by another user (see actions/checkout#956), thus failing the build on checkout.

This PR is NOT a permanent solution as we won't be able to update actions/checkout without switching to another image, but it will unblock other PRs with failing builds for now.

Type of change

• internal

How Has This Been Tested?

• Running the pipeline in CI

[codecov]

Codecov Report

Merging #3321 (21b0f33) into main (ef6fcdc) will increase coverage by 0.37%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3321      +/-   ##
==========================================
+ Coverage   93.04%   93.42%   +0.37%     
==========================================
  Files         226      241      +15     
  Lines        6517     7253     +736     
  Branches     1360     1507     +147     
==========================================
+ Hits         6064     6776     +712     
- Misses        453      477      +24     

Impacted Files	Coverage Δ
...emetry-core/src/platform/node/RandomIdGenerator.ts	87.50% <0.00%> (-6.25%)	⬇️
packages/opentelemetry-sdk-trace-web/src/utils.ts	95.00% <0.00%> (ø)
...-sdk-trace-web/src/enums/PerformanceTimingNames.ts	100.00% <0.00%> (ø)
...ckages/opentelemetry-sdk-trace-web/karma.worker.js	100.00% <0.00%> (ø)
...ntelemetry-resources/src/detectors/NoopDetector.ts	100.00% <0.00%> (ø)
...mentation-xml-http-request/src/enums/EventNames.ts	100.00% <0.00%> (ø)
...entelemetry-sdk-trace-web/src/WebTracerProvider.ts	100.00% <0.00%> (ø)
...ry-context-zone-peer-dep/src/ZoneContextManager.ts	85.18% <0.00%> (ø)
packages/opentelemetry-sdk-trace-web/src/types.ts	100.00% <0.00%> (ø)
...s/opentelemetry-instrumentation-fetch/src/fetch.ts	97.02% <0.00%> (ø)
... and 11 more