Corrections to image metadata check CI (#9256)

* don't just compare webp

* fix license check

.github/workflows/image_metadata.yml

@@ -34,11 +34,10 @@ jobs:
 
       - name: read/export image metadata
         run: |
-          mapfile -t image_files < <(git diff --name-only ${BASE_SHA} ${SHA} | grep '\.webp$')
-
+          mapfile -t image_files < <(git diff --name-only "$BASE_SHA" "$SHA" | grep -E '\.(webp|png|je?pg)$'))
           git status
           # array of accepted copyright strings
-          accepted_cr=("GNU GPL v2+" "CC BY-SA 4.0")
+          accepted_cr=("GNU GPL v2+|CC BY-SA 4.0|CC0")
           # cycle through the changed image files, make sure they have the right fields
           for file in "${image_files[@]}"; do
             # check -Artist tag, fail if missing
@@ -56,7 +55,7 @@ jobs:
             if [ -z "$copyright" ] ; then
               echo "no Copyright EXIF tag in $file"
               exit 1
-            elif [[ ( "$copyright" != ${accepted_cr[0]} ) && ( "$copyright" != ${accepted_cr[1]}) ]] ; then
+            elif [[ ! "|${accepted_cr[*]}|" =~ "|${copyright}|" ]]; then
               echo "$copyright is not an accepted license"
               exit 1
             else