Add permissions to run gradle task

Author: CJCrafter

.github/workflows/dokka-publish.yml

@@ -20,6 +20,9 @@ jobs:
           distribution: 'temurin'
           java-version: '11'
 
+      - name: Grant execute permission for gradlew
+        run: chmod +x gradlew
+
       - name: Generate Dokka HTML documentation
         run: ./gradlew dokkaHtml