Fix lowercase letter KeySym regressions #1304

Job	Run time
mypy	24s
ruff	18s
sdist	1m 38s
parse_sdl (windows-latest, 3.2.16)	40s
parse_sdl (macos-latest, 3.2.16)	22s
test-docs	2m 40s
build (ubuntu-latest, 3.10, x64)	4m 22s
build (windows-latest, pypy-3.10, x64)	4m 17s
linux-wheels (x86_64, cp310-manylinux*)	4m 11s
build (windows-latest, 3.10, x64)	3m 26s
tox (ubuntu-latest)	3m 51s
build-macos (cp310-*_universal2)	2m 1s
build-macos (pp310-*)	3m 42s
linux-wheels (x86_64, pp310-manylinux*)	3m 33s
build (ubuntu-latest, pypy-3.10, x64)	5m 2s
pyodide	4m 8s
linux-wheels (aarch64, pp310-manylinux*)	3m 34s
build (windows-latest, 3.10, x86)	3m 33s
linux-wheels (aarch64, cp310-manylinux*)	4m 5s
publish	0s
	55m 47s

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