d/apertis: Add missing copyright information

Signed-off-by: Ariel D'Alessandro <ariel.dalessandro@collabora.com>

debian/apertis/copyright.yml

+"*":
+  license: LGPL-2.1+ AND GPL-3+
+NEWS:
+  license: GFDL-1.3-or-later
+THANKS:
+  license: GFDL-1.3-or-later
+doc/*:
+  license: GFDL-1.3-or-later
+m4/ax_code_coverage.m4:
+  license: LGPL-2.1-or-later
+src/libopts/*:
+  license: GPL-3+
+tests/*:
+  license: GPL-3+
+.*/gnulib-cache.m4:
+  override-license: GPL-3+ WITH Autoconf-exception-2.0
+.*/gnulib-comp.m4:
+  override-license: GPL-3+ WITH Autoconf-exception-2.0
+.*/gtk-doc.m4:
+  override-license: GPL-3+ WITH Autoconf-exception-2.0