Upgrade node to 20 in github action #127

Job	Run time
tests_node	12s
Test on Python 3.8 and Django 3.2 on postgres	1m 14s
Test on Python 3.9 and Django 3.2 on postgres	1m 9s
Test on Python 3.10 and Django 3.2 on postgres	1m 27s
Test on Python 3.8 and Django 4.0 on postgres	58s
Test on Python 3.9 and Django 4.0 on postgres	1m 6s
Test on Python 3.10 and Django 4.0 on postgres	1m 16s
Test on Python 3.8 and Django 4.1 on postgres	56s
Test on Python 3.9 and Django 4.1 on postgres	1m 5s
Test on Python 3.10 and Django 4.1 on postgres	55s
Test on Python 3.11 and Django 4.1 on postgres	58s
Test on Python 3.8 and Django 4.2 on postgres	1m 36s
Test on Python 3.9 and Django 4.2 on postgres	1m 8s
Test on Python 3.10 and Django 4.2 on postgres	58s
Test on Python 3.11 and Django 4.2 on postgres	55s
Test on Python 3.12 and Django 4.2 on postgres	56s
Test on Python 3.10 and Django 5.0 on postgres	1m 2s
Test on Python 3.11 and Django 5.0 on postgres	1m 0s
Test on Python 3.12 and Django 5.0 on postgres	1m 8s
Test on Python 3.8 and Django 3.2 on sqlite	55s
	20m 54s

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