Refactor script: Do not check removed scripts

doc.zih.tu-dresden.de/util/check-bash-syntax.sh

@@ -52,7 +52,7 @@ elif [[ ! -z "${file}" ]]; then
   files=${file}
 else
   echo "Search in git-changed files."
-  files=`git diff --name-only "$(git merge-base HEAD "${branch}")" | grep '\.sh$' || true`
+  files=`git diff --name-only --diff-filter=d "$(git merge-base HEAD "${branch}")" | grep '\.sh$' || true`
 fi