Rename Ri(x) to RiemannR(x) #68

Job	Run time
linux_gcc_sanitizers	2m 18s
linux_gcc_valgrind	1m 20s
linux_gcc (ubuntu-latest, Debug)	4m 33s
linux_clang (ubuntu-latest, Debug)	3m 29s
linux_gcc (ubuntu-latest, Release)	2m 3s
linux_clang (ubuntu-latest, Release)	1m 16s
macos_clang (macos-latest, Debug)	5m 30s
macos_clang (macos-latest, Release)	6h 0m 15s
windows_mingw64 (windows-latest, Debug)	5m 16s
windows_msvc2022	2m 2s
windows_mingw64 (windows-latest, Release)	2m 54s
	6h 30m 56s

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