audit: don't allow both sha256 and tag/revision for formula

[dtrodrigues]

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes? Here's an example.
• Have you successfully run brew style with your changes locally?
• Have you successfully run brew tests with your changes locally?

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There are a few cases where formulae started using a source archive with a sha checksum and later moved to a git checkout with a tag/revision. In the best case case, the sha is no longer irrelevant to the git repository and in general it is out of date. This style check will detect and flag cases where a formula both has a sha256 as well as a tag and revision in the url.

CI is expected to fail until changes to the formulae below are incorporated.

$ brew style homebrew/core
== aws-iam-authenticator.rb ==
C:  7:  3: Do not use both sha and tag/revision.
== krew.rb ==
C:  7:  3: Do not use both sha and tag/revision.
== ksync.rb ==
C:  7:  3: Do not use both sha and tag/revision.
== kubeseal.rb ==
C:  7:  3: Do not use both sha and tag/revision.
== mage.rb ==
C:  7:  3: Do not use both sha and tag/revision.
== shogun.rb ==
C:  7:  3: Do not use both sha and tag/revision.
== solarus.rb ==
C:  7:  3: Do not use both sha and tag/revision.

5200 files inspected, 7 offenses detected

[MikeMcQuaid]

One tweak but good to ship then (when CI is green). Good catch!