fix: Package installers CI step failing

[davidgamez]

Summary:

As described in #1567, the Github actions associated with the MacOS certificate imports, notarization, and stapling were dependent on open-source projects that are not available anymore. This PR implements the MacOS certificate imports, notarization, and stapling using XCode terminal commands.

Fixes #1567

Expected behavior:

GTFS Validator App is signed and notarized.

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• Format the title like "feat: [new feature short description]". Title must follow the Conventional Commit Specification(https://www.conventionalcommits.org/en/v1.0.0/).
• Linked all relevant issues
• Include screenshot(s) showing how this pull request works and fixes the issue(s)

[davidgamez]

Screenshot of the downloaded app showing properly notarized. Look for text ...Apple checked it for malicious software and none was detected....

[github-actions]

✅ Rule acceptance tests passed.
New Errors: 0 out of 1470 datasets (~0%) are invalid due to code change, which is less than the provided threshold of 1%.
Dropped Errors: 0 out of 1470 datasets (~0%) are invalid due to code change, which is less than the provided threshold of 1%.
New Warnings: 0 out of 1470 datasets (~0%) are invalid due to code change, which is less than the provided threshold of 1%.
Dropped Warnings: 0 out of 1470 datasets (~0%) are invalid due to code change, which is less than the provided threshold of 1%.
0 out of 1470 sources (~0 %) are corrupted.
Commit: 1117d07
Download the full acceptance test report here (report will disappear after 90 days).
✅ Rule acceptance tests passed.