Devops: Update the `conda-incubator/setup-miniconda` action to v3 #291

Job	Run time
ubuntu-apt-2004 (3.7)	29s
ubuntu-apt (3.8)	29s
multi-conda (3.8, macos-12)	1m 13s
ubuntu-apt (3.11)	26s
multi-conda (3.8, windows-2022)	3m 21s
pre-commit	27s
ubuntu-postgres-action (3.9, testpw)	33s
ubuntu-postgres-service (3.9, testpw)	45s
	7m 43s

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