[WebTest] Add stubs (#14541) #15525

Job	Run time
stubtest: stdlib (ubuntu-latest, 3.13)	35s
stubtest: stdlib (macos-latest, 3.14)	35s
stubtest: stdlib (ubuntu-latest, 3.11)	33s
stubtest: stdlib (macos-latest, 3.12)	37s
stubtest: stdlib (macos-latest, 3.15)	59s
stubtest: stdlib (ubuntu-latest, 3.10)	50s
stubtest: stdlib (windows-latest, 3.12)	1m 47s
stubtest: stdlib (macos-latest, 3.11)	47s
stubtest: stdlib (windows-latest, 3.14)	1m 32s
stubtest: stdlib (macos-latest, 3.10)	48s
stubtest: stdlib (ubuntu-latest, 3.15)	46s
stubtest: stdlib (ubuntu-latest, 3.14)	38s
stubtest: stdlib (windows-latest, 3.11)	1m 16s
stubtest: stdlib (windows-latest, 3.13)	1m 18s
stubtest: stdlib (macos-latest, 3.13)	32s
stubtest: stdlib (windows-latest, 3.15)	2m 13s
stubtest: stdlib (ubuntu-latest, 3.12)	38s
	16m 24s

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