Upgrade notarization from altool to notarytool

[danyeaw]

Fixes #2781.

PR Checklist

Please check if your PR fulfills the following requirements:

• I have read, and I am following the Contributor guide
• I have read, and I understand the GNOME Code of Conduct

PR Type

What kind of change does this PR introduce?

• Bug fix
• Feature
• Chore (refactoring, formatting, local variables, other cleanup)
• Documentation content changes

What is the current behavior?

altool is used for notarization using GitHub Actions

Issue Number: N/A

What is the new behavior?

Use notarytool and stapler directly.

Does this PR introduce a breaking change?

• Yes
• No

Other information

[danyeaw]

@amolenaar I overrode the mainline build flag for testing this, and it passed all tests 👍

[amolenaar]

Looks good.

[amolenaar]

Checked it on macOS: Image build on the main branch works fine.

Output from codesign also looks okay:

$ codesign -dv /Volumes/Gaphor\ 2.21.0.dev4109+70167238/Gaphor.app
Executable=/Volumes/Gaphor 2.21.0.dev4109+70167238/Gaphor.app/Contents/MacOS/gaphor
Identifier=org.gaphor.gaphor
Format=app bundle with Mach-O thin (x86_64)
CodeDirectory v=20500 size=63133 flags=0x10000(runtime) hashes=1962+7 location=embedded
Signature size=8973
Timestamp=4 Nov 2023 at 09:41:39
Info.plist entries=21
TeamIdentifier=Z7V37BLNR9
Runtime Version=11.3.0
Sealed Resources version=2 rules=13 files=4598
Internal requirements count=1 size=180