Fix regex for username mentions #3335

Job	Run time
Pre-commit checks	4m 57s
Integration Tests (f38)	6m 28s
Build Documentation (f38)	2m 18s
Integration Tests (f39)	6m 27s
Build Documentation (f39)	2m 13s
Integration Tests (rawhide)	9m 15s
Build the RPMS (f38)	2m 13s
Build Documentation (pip)	3m 45s
Build the RPMS (f39)	2m 39s
Build Documentation (rawhide)	2m 2s
Build the RPMS (rawhide)	1m 57s
Unit Tests (f38, bodhi-client)	2m 35s
Unit Tests (f38, bodhi-messages)	1m 57s
Unit Tests (f38, bodhi-server)	6m 12s
Unit Tests (f39, bodhi-client)	1m 57s
Unit Tests (f39, bodhi-messages)	1m 45s
Unit Tests (f39, bodhi-server)	6m 26s
Unit Tests (pip, bodhi-client)	3m 20s
Unit Tests (pip, bodhi-messages)	3m 18s
Unit Tests (pip, bodhi-server)	8m 2s
Unit Tests (rawhide, bodhi-client)	1m 55s
Unit Tests (rawhide, bodhi-messages)	1m 21s
Unit Tests (rawhide, bodhi-server)	8m 22s
Diff-cover check	21s
	1h 31m 45s

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