more robust conversion to pyarrow for output #665

Job	Run time
linux-64-py3.10	5m 5s
prototype_mtc	48m 45s
prototype_mtc	47m 41s
prototype_psrc_in_development	3m 38s
estimation_mode_test	16m 10s
macOS	7m 15s
prototype_arc	53m 6s
win-64	10m 44s
random_seed_generation_test	2m 22s
placeholder_psrc	38m 55s
prototype_marin	1m 26s
prototype_mtc_extended	2h 59m 56s
develop-docbuild	0s
placeholder_sandag	2h 18m 6s
prototype_sandag_xborder	4m 57s
production_semcog	5m 14s
prototype_mwcog	47m 21s
placeholder_multiple_zone	7m 53s
	10h 18m 34s

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