[Fix #1474] Make `Rails/EnumSyntax` include the lib directory by default #714

Job	Run time
Check documentation syntax	11s
Spec - JRuby	2m 34s
Spec - 2.7	34s
Spec - 3.1	27s
Spec - 3.0	28s
Spec - 3.2	19s
Spec - 3.4	19s
Prism	34s
Spec - 3.3	19s
Check the oldest supported RuboCop version	29s
Spec - head	16s
	6m 30s

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