fix ambiguous regex warnings (#720) #370

Job	Run time
Unit test (ubuntu-20.04, 2.1)	58s
Unit test (ubuntu-20.04, 2.2)	1m 9s
Unit test (ubuntu-20.04, 2.3)	1m 7s
Unit test (ubuntu-20.04, 2.4)	56s
Unit test (ubuntu-20.04, 2.5)	28s
Unit test (ubuntu-20.04, 2.6)	32s
Unit test (ubuntu-20.04, 2.7)	27s
Unit test (ubuntu-20.04, 3)	17s
Unit test (ubuntu-20.04, 3.1)	19s
Unit test (ubuntu-20.04, 3.2)	16s
Unit test (ubuntu-20.04, 3.3)	18s
Unit test (ubuntu-20.04, jruby-9.1)	54s
Unit test (ubuntu-20.04, jruby-9.2)	1m 1s
Unit test (ubuntu-20.04, jruby-9.3)	48s
Unit test (ubuntu-20.04, jruby-9.4)	56s
Unit test (ubuntu-20.04, truffleruby)	1m 54s
Unit test (macos-latest, 2.6)	53s
Unit test (macos-latest, 2.7)	39s
Unit test (macos-latest, 3)	30s
Unit test (macos-latest, 3.1)	21s
Unit test (macos-latest, 3.2)	19s
Unit test (macos-latest, 3.3)	19s
Unit test (macos-latest, jruby-9.3)	36s
Unit test (macos-latest, jruby-9.4)	45s
Unit test (macos-latest, truffleruby)	1m 17s
Unit test (windows-latest, 2.2)	1m 43s
Unit test (windows-latest, 2.3)	1m 43s
Unit test (windows-latest, 2.4)	1m 27s
Unit test (windows-latest, 2.5)	2m 1s
Unit test (windows-latest, 2.6)	3m 12s
Unit test (windows-latest, 2.7)	2m 26s
Unit test (windows-latest, 3)	2m 37s
Unit test (windows-latest, 3.1)	1m 18s
Unit test (windows-latest, 3.2)	1m 35s
Unit test (windows-latest, 3.3)	1m 56s
finish	2s
	37m 59s

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