Remove Travis CI configuration #7

Job	Run time
build (gemfiles/Gemfile.activerecord-5.0, 2.4)	2m 27s
build (gemfiles/Gemfile.activerecord-5.2, 2.4)	2m 29s
build (gemfiles/Gemfile.activerecord-7.0, 2.7)	2m 11s
build (gemfiles/Gemfile.activerecord-8.0, 3.2)	1m 54s
build (gemfiles/Gemfile.activerecord-7.1, 2.7)	2m 5s
build (gemfiles/Gemfile.activerecord-6.1, 2.5)	1m 59s
build (gemfiles/Gemfile.activerecord-5.1, 2.4)	2m 26s
build (gemfiles/Gemfile.activerecord-6.0, 2.5)	1m 59s
build (gemfiles/Gemfile.activerecord-7.2, 3.1)	1m 43s
	19m 13s

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