fix(build): bower-material-release should force remove the stale layo…

…ut files.

* Currently an error occurs, when then file is not existing, using `-f` is ignoring that message and won't prevent the execution.

Closes #7807

scripts/bower-material-release.sh

@@ -25,8 +25,8 @@ function run {
 
   cd bower-material
   # remove stale layout files; newer ones are in `dist/layouts/`
-  rm ./angular-material.layouts.css
-  rm ./angular-material.layouts.min.css
+  rm -f ./angular-material.layouts.css
+  rm -f ./angular-material.layouts.min.css
 
 
   echo "-- Committing and tagging..."