Faster CI: Sparse run matrix, cancel previous jobs on the same branch #1934

Job	Run time
Generate build matrix for Conan CI	4s
fmtlib gsl-lite C++20 Apple Clang 15 Debug	1s
fmtlib none C++20 Apple Clang 15 Release	1s
fmtlib gsl-lite C++20 Clang-16 (x86-64) Debug	8m 10s
fmtlib none C++20 Clang-16 (x86-64) Release	3m 14s
fmtlib none C++20 Clang-17 (x86-64) Debug	9m 34s
std::format gsl-lite C++20 Clang-17 (x86-64) Debug	9m 49s
std::format gsl-lite C++20 Clang-18 (arm64) Debug	1s
fmtlib none C++23 Clang-18 (arm64) Release	1s
std::format gsl-lite C++20 Clang-18 (x86-64) Debug	10m 0s
std::format none C++23 Clang-18 (x86-64) Debug	10m 0s
fmtlib gsl-lite C++20 GCC-12 Debug	4m 38s
fmtlib ms-gsl C++20 GCC-12 Release	2m 1s
fmtlib ms-gsl C++23 GCC-12 Debug	4m 44s
std::format gsl-lite C++20 GCC-13 Debug	6m 18s
std::format none C++20 GCC-13 Release	2m 21s
fmtlib none C++20 GCC-14 Release	2m 4s
std::format gsl-lite C++20 GCC-14 Debug	5m 26s
fmtlib gsl-lite C++20 MSVC 14.4 Debug	2m 6s
std::format gsl-lite C++20 MSVC 14.4 Debug	1m 39s
Promote Conan package	1s
	1h 22m 13s

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