Do not hold Python's GIL when running commands #49

Job	Run time
codecheck / codecheck	44m 44s
docker / docker (fedora39)	18m 56s
conda / conda (ubuntu-20.04)	12m 5s
conda / conda (macos-12)	12m 6s
linux / linux (-doc-mpi-)	40m 1s
conda / conda (macos-14)	4m 34s
docker / docker (rocky8)	22m 54s
mac / macports (macos-12)	16m 47s
linux / linux (-mpi-)	52m 44s
mac / macports (macos-14)	3m 20s
linux / linux (-coverage-mpi-)	1h 2m 27s
mac / macports (+allmodules, macos-12)	32m 38s
mac / macsimple (macos-12)	12m 43s
linux / linux (-debug-)	31m 22s
mac / macsimple (macos-14)	5m 48s
linux / linux (-debug-mpi-)	42m 48s
linux / linux (-intel-)	45m 10s
linux / linux (-pycv-mpi-)	19m 39s
	8h 0m 46s

Provide feedback