Bug 32994: Remove breaking css/maps/*.map files from Makefile.PL

Bug 32994: Remove breaking css/maps/*.map files from Makefile.PL

to test:
 - run makefile, note failure

  $ perl Makefile.PL
  $ make
  $ make install
  webpack 5.74.0 compiled with 3 warnings in 20831 ms
  Done in 36.01s.
  make: *** No rule to make target 'koha-tmpl/opac-tmpl/bootstrap/css/maps/opac-rtl.css.map', needed by 'pm_to_blib'.  Stop.

 - apply patch
 - run makefile, note success

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>