* Fix Romanian language strings: replace U+015F with proper U+0219 * Update (c) in file headers and LICENSE * Update Australia holidays * Update Makefile clean action * Update US tests: Day After Thanksgiving * Update United Kingdom holidays: fix observed New Year's Day in Scotland * Update tests: use assertIsInstance * Fix README layout (attempt 1) * Add file header pre-commit check * Add package build tests * Unify file headers after recent update OBS-URL: https://build.opensuse.org/package/show/devel:languages:python/python-holidays?expand=0&rev=36