Use env var, fix chmod, correct path

Author: SolarLabyrinth

.github/workflows/test.yml

@@ -29,4 +29,4 @@ jobs:
           key: ${{ secrets.BUTLER_API_KEY }}
 
       - name: Upload to Itch
-        run: butler push ./build solarlabyrinth/github-action-test:windows
+        run: butler push ./project/build solarlabyrinth/github-action-test:windows

action.yml

@@ -28,7 +28,7 @@ runs:
 
         cd $INSTALL_DIR
 
-        wget -O butler.zip https://broth.itch.ovh/butler/linux-amd64/LATEST/archive/default
+        wget -O butler.zip $BUTLER_DOWNLOAD_URL
         unzip butler.zip
         rm -rf butler.zip
 
@@ -44,3 +44,4 @@ runs:
       run: |
         mkdir -p ~/.config/itch
         echo "${{ inputs.key }}" > ~/.config/itch/butler_creds
+        chmod 600 ~/.config/itch/butler_creds