⬆️ Bump libs/Catch2 from `a6ee7e2` to `9c5a4cf` #350

Job	Run time
ubuntu-20.04 with g++-9 (Debug mode)	1m 12s
ubuntu-20.04 with g++-9 (Release mode)	1m 15s
ubuntu-20.04 with g++-10 (Debug mode)	1m 12s
ubuntu-20.04 with g++-10 (Release mode)	1m 17s
ubuntu-20.04 with clang++-10 (Debug mode)	1m 20s
ubuntu-20.04 with clang++-10 (Release mode)	1m 17s
ubuntu-20.04 with clang++-11 (Debug mode)	1m 9s
ubuntu-20.04 with clang++-11 (Release mode)	57s
ubuntu-20.04 with clang++-12 (Debug mode)	1m 9s
ubuntu-20.04 with clang++-12 (Release mode)	55s
ubuntu-22.04 with g++-9 (Debug mode)	1m 23s
ubuntu-22.04 with g++-9 (Release mode)	1m 9s
ubuntu-22.04 with g++-10 (Debug mode)	1m 1s
ubuntu-22.04 with g++-10 (Release mode)	1m 23s
ubuntu-22.04 with clang++-11 (Debug mode)	1m 52s
ubuntu-22.04 with clang++-11 (Release mode)	1m 8s
ubuntu-22.04 with clang++-12 (Debug mode)	1m 36s
ubuntu-22.04 with clang++-12 (Release mode)	1m 41s
	22m 56s

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