fix: support PEP 604 structured output unions #2109

Job	Run time
checks / readme-snippets	11s
checks / pre-commit	35s
checks / test (3.11, lowest-direct, ubuntu-latest)	56s
checks / test (3.10, locked, windows-latest)	2m 43s
checks / test (3.10, locked, ubuntu-latest)	1m 1s
checks / test (3.11, lowest-direct, windows-latest)	3m 30s
checks / test (3.10, lowest-direct, ubuntu-latest)	1m 0s
checks / test (3.11, locked, ubuntu-latest)	52s
checks / test (3.12, locked, ubuntu-latest)	55s
checks / test (3.13, lowest-direct, windows-latest)	2m 42s
checks / test (3.12, locked, windows-latest)	3m 54s
checks / test (3.13, lowest-direct, ubuntu-latest)	58s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 15s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 4s
checks / test (3.11, locked, windows-latest)	2m 52s
checks / test (3.10, lowest-direct, windows-latest)	2m 28s
checks / test (3.14, locked, windows-latest)	3m 28s
checks / test (3.13, locked, windows-latest)	2m 34s
checks / test (3.12, lowest-direct, windows-latest)	3m 35s
checks / test (3.14, lowest-direct, windows-latest)	2m 22s
checks / test (3.14, locked, ubuntu-latest)	2m 23s
checks / test (3.13, locked, ubuntu-latest)	47s
all-green	2s
	42m 7s

Provide feedback