message: Fix URL for CLDR plurals.xml
  CLDR migrated to GitHub, redirecting the XML URL to HTML view.
diff: @@ -15,7 +15,7 @@ from tempfile import TemporaryDirectory
  import xml.etree.ElementTree as ET
  -TABLE_URL = "https://www.unicode.org/repos/cldr/tags/latest/common/supplemental/plurals.xml"
  +TABLE_URL = "https://github.com/unicode-org/cldr/raw/master/common/supplemental/plurals.xml"
  MARKER_BEGIN = "// Code generated with scripts/extract-plural-forms.py begins here"
  MARKER_END = "// Code generated with scripts/extract-plural-forms.py ends here"
  