Replaced Firefox with Chromium for Selenium tests #145

Job	Run time
Run tox environment quality	31s
build (Python 3.10, Django 4.2)	1m 7s
Visual tests	36s
Run tox environment dist-validation	20s
build (Python 3.10, Django 5.0)	1m 4s
build (Python 3.10, Django 5.1)	1m 3s
build (Python 3.10, Django main)	1m 35s
build (Python 3.11, Django 4.2)	1m 2s
build (Python 3.11, Django 5.0)	1m 7s
build (Python 3.11, Django 5.1)	1m 2s
build (Python 3.11, Django main)	1m 38s
build (Python 3.12, Django 4.2)	1m 14s
build (Python 3.12, Django 5.0)	1m 17s
build (Python 3.12, Django 5.1)	1m 13s
build (Python 3.12, Django main)	1m 47s
build (Python 3.8, Django 4.2)	1m 6s
build (Python 3.9, Django 4.2)	1m 13s
	18m 55s

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