Fix stale repos test

[alexbozhenko]

Fix the usage of the stale repo test. It has not been running since March 2023. Looks like this one is the last issue that was created by it: #4809

See discussion at #4871 (comment)
Currently, the stale_repository_test is invoked incorrectly. It does not accept the file name:
From go help test

usage: go test [build/test flags] [packages] [build/test flags & test binary flags]

'Go test' automates testing the packages named by the import paths.

If we look at the history of deletions, we will see that stuff is mostly added, and very occasionally deleted from this repo.

git log --pretty=format:"%h - %ad - %s" --shortstat -- README.md | grep -B1 'deletion' 

That results in lots of links to abandonware, which is not awesome at all.
Having that this website is mentioned at the very beginning of https://go.dev/wiki/, can we make it better?

Reproducible test plan:

1. export OAUTH_TOKEN=YOUR_TOKEN_FROM_GITHUB
2. go test -timeout 99999s -v -run ^TestStaleRepository$
   (for this run I removed the limit on number of stale repos, which is currently set to 10. Also, this will trigger github API ratelimit, which is 5000 requests per hour. I had to add delay between the calls.)
3. Check the issue it created: Investigate repositories with more than 1 year without update - 2023-12-11 #5136
   Note that out of 2413 github links in readme.md, 1217 were flagged as stale.

[github-actions]

Thank you for contributing with awesome-go, we will revise your contribution as soon as possible.

Make sure you add the links in the body of the pull request that are requested in the contribution guide:

• godoc.org or pkg.go.dev
• goreportcard.com
• coverage

your project is about to be approved, it's under revision, it may take a few days

[avelino]

LGTM