Do not hold Python's GIL when running commands #53

Job	Run time
docker / docker (fedora39)	21m 3s
codecheck / codecheck	43m 56s
docker / docker (rocky8)	23m 32s
linux / linux (-doc-mpi-)	41m 20s
conda / conda (ubuntu-20.04)	11m 13s
linux / linux (-mpi-)	50m 21s
conda / conda (macos-13)	18m 9s
linux / linux (-coverage-mpi-)	1h 4m 9s
conda / conda (macos-14)	4m 11s
mac / macports (macos-13)	19m 2s
linux / linux (-debug-)	29m 9s
mac / macsimple (macos-13)	11m 32s
mac / macports (macos-14)	2m 52s
linux / linux (-debug-mpi-)	43m 27s
mac / macsimple (macos-14)	6m 12s
mac / macports (+allmodules, macos-13)	26m 12s
linux / linux (-intel-)	43m 55s
linux / linux (-pycv-mpi-)	18m 12s
linux / linux (-nvhpc-mpi-)	55m 12s
	8h 53m 39s

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