AO3-6854 Bump reviewdog/action-rubocop from 2.19.1 to 2.20.0 #4712

Job	Run time
rake db:otwseed	1m 17s
rspec spec/controllers	11m 52s
rspec spec/models	5m 32s
rspec --exclude-pattern 'spec/{controllers,models}/*/.rb'	7m 35s
cucumber features/admins	6m 39s
cucumber features/bookmarks	4m 40s
cucumber features/collections	6m 26s
cucumber features/comments_and_kudos	7m 1s
cucumber features/gift_exchanges	7m 13s
cucumber features/importing	2m 52s
cucumber features/other_a	10m 40s
cucumber features/other_b	6m 7s
cucumber features/prompt_memes_a	3m 54s
cucumber features/prompt_memes_b	3m 46s
cucumber features/prompt_memes_c	5m 22s
cucumber features/search	6m 15s
cucumber features/tag_sets	3m 10s
cucumber features/tags_and_wrangling	6m 34s
cucumber features/users	5m 1s
cucumber features/works	13m 29s
	2h 5m 25s

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