Update Cambodia holidays: add Peace Day in Cambodia #5092

Job	Run time
Run pre-commit	32s
CodeQL	1m 45s
Test Python 3.9 on macos-latest	42s
Test Python 3.10 on macos-latest	40s
Test Python 3.11 on macos-latest	38s
Test Python 3.12 on macos-latest	51s
Test Python 3.13 on macos-latest	40s
Test Python 3.9 on ubuntu-latest	1m 2s
Test Python 3.10 on ubuntu-latest	55s
Test Python 3.11 on ubuntu-latest	52s
Test Python 3.12 on ubuntu-latest	1m 32s
Test Python 3.13 on ubuntu-latest	1m 9s
Test Python 3.9 on windows-latest	1m 45s
Test Python 3.10 on windows-latest	2m 11s
Test Python 3.11 on windows-latest	1m 32s
Test Python 3.12 on windows-latest	2m 8s
Test Python 3.13 on windows-latest	2m 1s
Test docs build	42s
Build distribution	22s
Test build on macos-latest	28s
Test build on ubuntu-latest	46s
Test build on windows-latest	2m 2s
Publish generated artifacts	0s
	25m 15s

Provide feedback