CI: Fix sync_class_ref.yml workflow

Author: Repiteo

.github/workflows/sync_class_ref.yml

@@ -56,7 +56,7 @@ jobs:
 
       - name: Build new documentation
         run: |
-          ./.engine-src/doc/tools/make_rst.py --color -o ./classes -l en ./.engine-src/doc/classes ./.engine-src/modules ./.engine-src/platform
+          python ./.engine-src/doc/tools/make_rst.py --color -o ./classes -l en ./.engine-src/doc/classes ./.engine-src/modules ./.engine-src/platform
 
       - name: Submit a pull-request
         uses: peter-evans/create-pull-request@v8