Fix incorrect TypingUnionType import check #9520

Job	Run time
📈 Benchmarks	3m 41s
💻 Generate test matrix	30s
✨ Lint	1m 45s
🪟 Tests on Windows	6m 37s
🔬 Tests on 3.12	2m 40s
🔬 Tests on 3.11	2m 12s
🔬 Tests on 3.10	2m 47s
🔬 Tests on 3.9	3m 6s
🔬 Tests on 3.8	2m 24s
🔬 Django tests on 3.11 (django=4.2.0)	2m 14s
🔬 Django tests on 3.11 (django=4.1.0)	1m 49s
🔬 Django tests on 3.11 (django=4.0.0)	2m 16s
🔬 Django tests on 3.11 (django=3.2.0)	1m 45s
🔬 Starlette tests on 3.11 (starlette=0.28.0)	1m 42s
🔬 Starlette tests on 3.11 (starlette=0.27.0)	1m 55s
🔬 Starlette tests on 3.11 (starlette=0.26.1)	2m 16s
🔬 Test integrations on 3.11 (integration=aiohttp)	2m 16s
🔬 Test integrations on 3.11 (integration=chalice)	1m 49s
🔬 Test integrations on 3.11 (integration=channels)	2m 15s
🔬 Test integrations on 3.11 (integration=fastapi)	2m 3s
🔬 Test integrations on 3.11 (integration=flask)	1m 41s
🔬 Test integrations on 3.11 (integration=sanic)	2m 15s
🔬 Test integrations on 3.11 (integration=starlite)	2m 19s
🔬 Pydantic tests on 3.11 (pydantic=1.10)	2m 16s
🔬 Pydantic tests on 3.11 (pydantic=2.0.3)	2m 14s
🔬 Pyright tests on 3.12	2m 0s
🔬 Pyright tests on 3.11	2m 22s
🔬 Pyright tests on 3.10	2m 16s
🔬 Pyright tests on 3.9	2m 32s
🔬 Pyright tests on 3.8	2m 2s
🔬 CLI tests on 3.12	1m 40s
🔬 CLI tests on 3.11	1m 58s
🔬 CLI tests on 3.10	1m 44s
🔬 CLI tests on 3.9	1m 44s
🔬 CLI tests on 3.8	1m 43s
	1h 18m 48s

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