ci: add shellcheck

.woodpecker/lint.yml

@@ -19,10 +19,17 @@ steps:
           - tag
 
   shellcheck:
-    image: koalaman/shellcheck-alpine:stable@sha256:f73b035c8ebfc8a66ba54e07af5cc41e790cf41fff45317914b1ce677dd9cada
+    image: registry.mgrote.net/allzweckcontainer
     commands:
-      - "find . -name *.sh -exec shellcheck {} +"
+      - |
+        find . -type f -not -path './.git/*' -not -path './collections/*' -exec file {} \; | while IFS= read -r line; do
+          if echo "$line" | grep -q "shell script"; then
+            file_path=$(echo "$line" | awk -F':' '{print $1}')
+            shellcheck "$file_path"
+          fi
+        done
     when:
       event:
         exclude:
           - tag
+...