CMake

Add tests when char_t is disabled on C++20. #93

Job	Run time
build (ubuntu-latest, Debug, clang)	30s
build (ubuntu-latest, Debug, gcc)	39s
build (ubuntu-latest, Debug, tcc)	44s
build (ubuntu-latest, RelWithDebInfo, clang)	30s
build (ubuntu-latest, RelWithDebInfo, gcc)	23s
build (ubuntu-latest, RelWithDebInfo, tcc)	23s
build (ubuntu-latest, MinSizeRel, clang)	19s
build (ubuntu-latest, MinSizeRel, gcc)	28s
build (ubuntu-latest, MinSizeRel, tcc)	13s
build (ubuntu-latest, Release, clang)	11s
build (ubuntu-latest, Release, gcc)	28s
build (ubuntu-latest, Release, tcc)	17s
build (windows-latest, Debug, default)	1m 14s
build (windows-latest, Debug, clang)	1m 36s
build (windows-latest, RelWithDebInfo, default)	1m 5s
build (windows-latest, RelWithDebInfo, clang)	1m 12s
build (windows-latest, MinSizeRel, default)	59s
build (windows-latest, MinSizeRel, clang)	1m 31s
build (windows-latest, Release, default)	30s
build (windows-latest, Release, clang)	1m 58s
build (macos-13, Debug, default)	14s
build (macos-13, RelWithDebInfo, default)	55s
build (macos-13, MinSizeRel, default)	19s
build (macos-13, Release, default)	21s
build (macos-latest, Debug, default)	25s
build (macos-latest, RelWithDebInfo, default)	10s
build (macos-latest, MinSizeRel, default)	44s
build (macos-latest, Release, default)	12s
	18m 30s

Provide feedback