ci-license-scan: Do not use _fg with sh

This is a special argument only useful for programs that need user
interaction.
The functionality side-steps a lot of sh's functionality which can cause
unstability in the output of the program.

See
https://amoffat.github.io/sh/sections/special_arguments.html#fg



Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>

package-source-builder/overlay/usr/bin/ci-license-scan

@@ -122,7 +122,7 @@ try:
 except:
     diff = sh.Command('diff')
 
-copyrightdiff = diff.bake('-au', '--label=approved-copyright', '--label=unapproved-copyright', _fg=True)
+copyrightdiff = diff.bake('-au', '--label=approved-copyright', '--label=unapproved-copyright', _out=sys.stdout, _err=sys.stderr)
 
 def merge_scan_patterns(*dicts):
     """