change installer miniconda to v3 #977

Job	Run time
linux-64-py3.10	5m 59s
macOS	6m 24s
win-64	14m 14s
random_seed_generation_test	3m 21s
Standard 1-Zone Example (MTC)	47m 4s
prototype_mtc	43m 47s
Standard 2-Zone Example (SANDAG)	59m 51s
placeholder_psrc	35m 48s
prototype_marin	2m 27s
develop-docbuild	0s
prototype_mtc_extended	1h 18m 56s
estimation_mode_test	17m 13s
placeholder_sandag	1h 35m 24s
prototype_sandag_xborder	5m 8s
production_semcog	5m 55s
prototype_mwcog	43m 35s
placeholder_multiple_zone	8m 51s
	7h 53m 57s

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