Add syntax error for empty type parameter list #29853

Job	Run time
pre-commit	1m 9s
python package	1m 19s
Determine changes	17s
cargo fmt	17s
mkdocs	2m 30s
cargo test (linux)	3m 36s
cargo test (windows)	8m 26s
cargo clippy	1m 41s
cargo build (msrv)	2m 58s
cargo build (release)	4m 27s
cargo fuzz	4m 9s
cargo test (wasm)	1m 16s
test scripts	56s
benchmarks	3m 53s
cargo shear	26s
formatter instabilities and black similarity	4m 4s
test ruff-lsp	29s
ecosystem	15m 23s
Fuzz the parser	5m 26s
	1h 2m 42s

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