Use lychee cache

[dmathieu]

A few months ago, we enabled lychee cache in the SDK repo, to prevent rate limit issues, but forgot to enable it here.
open-telemetry/opentelemetry-go#5160

[dmathieu]

Note that the check needs to succeed once for the cache to be stored (lychee doesn't update the cache if there's a failure anyway).

[pellared]

@dmathieu, this does not look like fixing the following issue:

• [429] https://github.com/open-telemetry/opentelemetry-go/commits/main | Failed: Network error: Too Many Requests

However, I am not against merging it as I think it is good to have the same CI configuration.

[dmathieu]

The check needs to run successfully once (we can trigger it at a moment of low activity) to trigger the cache.

[dmathieu]

If we can't ever run the check once, we'd either need to figure out a way to split the check (I don't think lychee can do that), or to add an auth token to the GitHub requests so the rate limit is increased.

Alternatively, lycheeverse/lychee#1403 would allow us to update the cache with only the successful checks, making failures retry only what didn't succeed previously. That PR is stalled, and I haven't been able to figure out its issue so far.

[pellared]

add an auth token to the GitHub requests so the rate limit is increased

I think this is the way. We just need to make sure to limit the permissions for GITHUB_TOKEN using https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/controlling-permissions-for-github_token#defining-access-for-the-github_token-permissions

My guess is that it just needs contents: read or even nothing 😉

Reference: https://github.com/lycheeverse/lychee/blob/master/docs/TROUBLESHOOTING.md#github-rate-limiting

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 66.8%. Comparing base (1c8a001) to head (9ed16ca).
Report is 1 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #6161   +/-   ##
=====================================
  Coverage   66.8%   66.8%           
=====================================
  Files        206     206           
  Lines      13211   13211           
=====================================
+ Hits        8833    8835    +2     
+ Misses      4111    4110    -1     
+ Partials     267     266    -1     

see 1 file with indirect coverage changes