When PR branch is unfortunately named, it can cause ambiguities in the git commands in GHA actions

[jiridanek]

https://github.com/red-hat-data-services/notebooks/actions/runs/11052380337/job/30704337780?pr=361

It seems that when PR branch is unfortunately named, it can cause ambiguities in the git commands.

+ git fetch --no-tags origin pull/361/head:amd
From https://github.com/red-hat-data-services/notebooks
 * [new ref]         refs/pull/361/head -> amd
+ git fetch --no-tags origin +refs/heads/main:refs/remotes/origin/main
From https://github.com/red-hat-data-services/notebooks
 * [new branch]      main       -> origin/main
+ python3 ci/cached-builds/gen_gha_matrix_jobs.py --from-ref origin/main --to-ref amd
INFO:root:Skipping targets not modified in the PR
DEBUG:root:Getting list of changed files from git diff
fatal: ambiguous argument 'amd': both revision and filename
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'
Traceback (most recent call last):
  File "/home/runner/work/notebooks/notebooks/ci/cached-builds/gen_gha_matrix_jobs.py", line 188, in <module>
    main()
  File "/home/runner/work/notebooks/notebooks/ci/cached-builds/gen_gha_matrix_jobs.py", line 172, in main
    changed_files = gha_pr_changed_files.list_changed_files(args.from_ref, args.to_ref)
  File "/home/runner/work/notebooks/notebooks/ci/cached-builds/gha_pr_changed_files.py", line 19, in list_changed_files
    files = subprocess.check_output(["git", "diff", "--name-only", from_ref, to_ref],
  File "/usr/lib/python3.10/subprocess.py", line 421, in check_output
    return run(*popenargs, stdout=PIPE, timeout=timeout, check=True,
  File "/usr/lib/python3.10/subprocess.py", line 526, in run
    raise CalledProcessError(retcode, process.args,
subprocess.CalledProcessError: Command '['git', 'diff', '--name-only', 'origin/main', 'amd']' returned non-zero exit status [12](https://github.com/red-hat-data-services/notebooks/actions/runs/11052380337/job/30704337780?pr=361#step:3:13)8.

[jiridanek]

Managed to reproduce for myself

$ mkdir amd
$ git diff --name-only origin/main amd
fatal: ambiguous argument 'amd': both revision and filename
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'

The fix is, as the error says, to do

$ git diff --name-only origin/main amd --