Only generate valid names for `FsPath` tests #280

Job	Run time
cabal-check (9.6.4, 3.10.3.0, ubuntu-latest)	2m 20s
cabal-fmt (9.6.4, 3.10.3.0, ubuntu-latest)	4m 18s
stylish-haskell (9.6.4, 3.10.3.0, ubuntu-latest)	3m 19s
build (8.10.7, 3.10.3.0, ubuntu-latest)	2m 19s
build (8.10.7, 3.10.3.0, windows-latest)	3m 52s
build (8.10.7, 3.10.3.0, macOS-13)	3m 7s
build (9.2.8, 3.10.3.0, ubuntu-latest)	2m 17s
build (9.2.8, 3.10.3.0, windows-latest)	4m 53s
build (9.2.8, 3.10.3.0, macOS-13)	2m 42s
build (9.4.8, 3.10.3.0, ubuntu-latest)	3m 24s
build (9.4.8, 3.10.3.0, windows-latest)	4m 38s
build (9.4.8, 3.10.3.0, macOS-13)	5m 52s
build (9.6.4, 3.10.3.0, ubuntu-latest)	3m 15s
build (9.6.4, 3.10.3.0, windows-latest)	6m 5s
build (9.6.4, 3.10.3.0, macOS-13)	6m 9s
build (9.8.2, 3.10.3.0, ubuntu-latest)	1m 16s
build (9.8.2, 3.10.3.0, windows-latest)	4m 54s
build (9.8.2, 3.10.3.0, macOS-13)	6m 8s
	1h 10m 48s

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