Be more lenient in ignoring LICENSE and COPYING-like files

[carmenbianca]

Fixes #1032.

Also ignore such files separated by a dash instead of a full stop.

Also ignore the UK spelling LICENCE.

• [x] Added a change log entry in changelog.d/<directory>/.
• [x] Wrote tests.
• [ ] Documented my changes in docs/man/ or elsewhere.
• [ ] My changes do not contradict the current specification.
• [x] I agree to license my contribution under the licenses indicated in the changed files.