Add workaround to retry git clone failures

GitHub infrastructure issues (on GitHub-hosted runners):
https://support.github.com/ticket/2884386
https://support.github.com/ticket/2983134

related bug reports (for first ticket):
https://github.com/actions/upload-artifact/issues/560#issuecomment-2178444482
https://github.com/actions/upload-artifact/issues/569#issuecomment-2188730144
https://github.com/actions/download-artifact/issues/338

example issue: https://github.com/canonical/mysql-k8s-operator/actions/runs/11246458889/job/31268560569#step:22:47
```
determining package name from 'git+https://github.com/canonical/jhack'...
error: subprocess-exited-with-error

× git clone --filter=blob:none --quiet https://github.com/canonical/jhack /tmp/pip-req-build-ievseulf did not run successfully.
│ exit code: 128
╰─> [1 lines of output]
fatal: unable to access 'https://github.com/canonical/jhack/': Failed to connect to github.com port 443 after 132796 ms: Connection timed out
[end of output]

note: This error originates from a subprocess, and is likely not a problem with pip.
error: subprocess-exited-with-error

× git clone --filter=blob:none --quiet https://github.com/canonical/jhack /tmp/pip-req-build-ievseulf did not run successfully.
│ exit code: 128
╰─> See above for output.
```