[`pyupgrade`] Handle multiple base classes for PEP 695 generics (`UP046`) #39368

Job	Run time
Determine changes	12s
cargo build (release)	0s
cargo fmt	17s
mkdocs	2m 37s
pre-commit	3m 14s
python package	1m 22s
benchmarks	5m 3s
cargo fuzz build	4m 55s
cargo build (msrv)	4m 26s
cargo clippy	1m 50s
cargo shear	23s
cargo test (linux)	1m 48s
cargo test (linux, release)	4m 9s
cargo test (wasm)	1m 47s
cargo test (windows)	4m 21s
formatter instabilities and black similarity	0s
test scripts	1m 8s
ecosystem	2m 40s
test ruff-lsp	43s
fuzz parser	0s
	40m 55s

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