Use relative submodule paths to facilitate forking. (#111) #414

Job	Run time
sanitizer - debian:bookworm \|	2m 25s
sanitizer - arm32v7/debian:bookworm \| ubuntu-24.04-arm	2m 17s
coverage - measure	3m 11s
sanitizer - arm64v8/debian:bookworm \| ubuntu-24.04-arm	2m 12s
conan - macos-latest	2m 25s
msvs	11m 22s
android	4m 10s
vcpkg - linux \|	3m 9s
conan - emscripten \|	3m 7s
linux - debian:bookworm	2m 47s
linux - ubuntu:noble	2m 18s
ios	1m 52s
msys2 - mingw32	4m 40s
msys2 - mingw64	3m 40s
linux - arm32v7/debian:bookworm	3m 21s
conan - linux \|	2m 24s
linux - arm64v8/debian:bookworm	2m 51s
macosx	4m 58s
	1h 3m 9s

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