[Backport 1.5.latest] Pin `macos` runners to `macos-12` (#787) #5513

Job	Run time
code-quality	1m 34s
build packages	19s
unit test / python 3.8	3m 42s
unit test / python 3.9	3m 42s
unit test / python 3.10	41m 4s
unit test / python 3.11	57m 25s
verify packages / python 3.8 / ubuntu-latest	38s
verify packages / python 3.9 / ubuntu-latest	38s
verify packages / python 3.10 / ubuntu-latest	42s
verify packages / python 3.11 / ubuntu-latest	39s
verify packages / python 3.8 / macos-12	1m 4s
verify packages / python 3.9 / macos-12	1m 23s
verify packages / python 3.10 / macos-12	1m 25s
verify packages / python 3.11 / macos-12	1m 25s
verify packages / python 3.8 / windows-latest	1m 38s
verify packages / python 3.9 / windows-latest	2m 32s
verify packages / python 3.10 / windows-latest	2m 37s
verify packages / python 3.11 / windows-latest	2m 58s
	2h 5m 25s

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