Allow year range in copyright strings
Allow year range in copyright strings

Fixes https://github.com/googlefonts/fontbakery/issues/2393

googlefonts/fontbakery,moyogo/fontbakery,graphicore/fontbakery,googlefonts/fontbakery,graphicore/fontbakery,graphicore/fontbakery,googlefonts/fontbakery,moyogo/fontbakery,moyogo/fontbakery