[red-knot] Do not panic when encountering string annotations #34991

Job	Run time
cargo fmt	18s
pre-commit	39s
Determine changes	8s
mkdocs	2m 45s
python package	1m 24s
cargo test (windows)	8m 35s
cargo test (wasm)	1m 28s
cargo test (linux)	4m 4s
cargo build (msrv)	3m 42s
cargo build (release)	5m 37s
cargo clippy	1m 51s
cargo fuzz	4m 31s
benchmarks	4m 39s
cargo shear	22s
test scripts	57s
formatter instabilities and black similarity	0s
ecosystem	8m 45s
test ruff-lsp	14s
Fuzz the parser	0s
	49m 59s

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