[`flake8-type-checking`] Add a fix for `runtime-string-union` (`TC010`) #39737

Job	Run time
cargo build (release)	0s
mkdocs	2m 26s
cargo fmt	17s
Determine changes	9s
pre-commit	3m 7s
python package	1m 20s
cargo fuzz build	4m 11s
cargo clippy	1m 46s
cargo build (msrv)	4m 54s
benchmarks	4m 50s
cargo test (linux)	2m 0s
cargo shear	26s
cargo test (wasm)	1m 33s
cargo test (linux, release)	4m 1s
cargo test (windows)	4m 27s
test scripts	59s
formatter instabilities and black similarity	0s
test ruff-lsp	39s
fuzz parser	0s
ecosystem	2m 46s
	39m 51s

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