style: use parentheses for assignment in conditions

[nandahkrishna]

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This PR removes all Lint/AssignmentInCondition violations, which was listed as a # TODO in .rubocop.yml.

(Parentheses must be used to enclose assignment statements within conditions.)

[BrewTestBot]

Review period will end on 2021-02-15 at 13:05:57 UTC.

[BrewTestBot]

Review period ended.