Update action to use variable substitution

.github/workflows/draft-release.yaml

@@ -29,13 +29,13 @@ jobs:
         if: ${{ steps.check-tag.outputs.exists == 'true' }}
         run: exit 1
 
-      - name: Move system.json to a temp file
-        id: manifest-move
-        run: mv system.json module.temp.json
-
-      - name: Update the download property in the manifest
+      - name: Update the manifest with the relevant properties
         id: manifest-update
-        run: cat module.temp.json | jq -r --tab '.download = "https://github.com/${{ github.repository }}/releases/download/v${{ steps.version.outputs.version }}/release.zip"' > system.json
+        uses: microsoft/variable-substitution@v1
+        with:
+          files: "system.json"
+        env:
+          download: "https://github.com/${{ github.repository }}/releases/download/v${{ steps.version.outputs.version }}/release.zip"
 
       - name: Create the zip
         run: zip -r release.zip system.json module langs assets templates README.md