fix: resolve double-prefixed path in .unitypackage generation

metaList paths were absolute (upm-package/...) but project-folder
also prepended upm-package/, causing ENOENT. Now writes paths
relative to upm-package/ so the action resolves them correctly.

Author: endel

.github/workflows/unity-upm-release.yml

@@ -174,8 +174,9 @@ jobs:
 
     - name: Gather meta files
       run: |
-        find upm-package/ -name '*.meta' > metaList
-        cat metaList
+        cd upm-package
+        find . -name '*.meta' | sed 's|^\./||' > ../metaList
+        cat ../metaList
 
     - name: Extract Version
       id: version