Guard `Packer` buffer protocol hooks with Cython critical sections #448

Job	Run time
Run test with Python 3.15 on ubuntu-latest	37s
Run test with Python 3.10 on ubuntu-latest	34s
Run test with Python 3.14t on ubuntu-latest	1m 14s
Run test with Python 3.15t on ubuntu-latest	1m 14s
Run test with Python 3.14 on windows-latest	1m 15s
Run test with Python 3.15t on macos-latest	1m 35s
Run test with Python 3.15 on windows-latest	1m 37s
Run test with Python 3.13 on ubuntu-latest	31s
Run test with Python 3.12 on ubuntu-latest	30s
Run test with Python 3.15t on windows-latest	2m 34s
Run test with Python 3.15 on macos-latest	1m 11s
Run test with Python 3.12 on windows-latest	55s
Run test with Python 3.10 on macos-latest	50s
Run test with Python 3.14t on windows-11-arm	3m 2s
Run test with Python 3.15 on windows-11-arm	2m 19s
Run test with Python 3.11 on windows-11-arm	2m 11s
Run test with Python 3.13 on windows-latest	50s
Run test with Python 3.14 on ubuntu-latest	29s
Run test with Python 3.14t on macos-latest	1m 16s
Run test with Python 3.10 on windows-latest	1m 32s
Run test with Python 3.11 on windows-latest	57s
Run test with Python 3.12 on windows-11-arm	1m 6s
Run test with Python 3.13 on macos-latest	27s
Run test with Python 3.14 on macos-latest	39s
Run test with Python 3.12 on macos-latest	39s
Run test with Python 3.11 on macos-latest	34s
Run test with Python 3.14 on windows-11-arm	1m 57s
Run test with Python 3.13 on windows-11-arm	1m 2s
Run test with Python 3.14t on windows-latest	2m 31s
Run test with Python 3.15t on windows-11-arm	2m 41s
Run test with Python 3.11 on ubuntu-latest	30s
	39m 19s

Provide feedback