doc: Rolf Bensch is no longer a maintainer for the pixma backend.

AUTHORS

@@ -78,7 +78,7 @@ Backends:
                 Nicolas Martin
                 Louis Lagendijk (*)
                 Dennis Lou
-                Rolf Bensch (*)
+                Rolf Bensch
                 Povilas Kanapickas (*)
  plustek:       Gerhard Jaeger (*)
  plustek_pp:    Rick Bronson (former pp driver-code), Gerhard Jaeger (*)