ci(update): Checkout repo after running Node.js steps

Ensures the workspace is clean before attempting to update any file.
Removes the need for explicitly ignoring Node.js artifacts in Git, since
they get cleaned up by the 'checkout' action before fetching.

.github/workflows/update.yml

@@ -21,10 +21,6 @@ jobs:
             branch: release-6.x
 
     steps:
-      - uses: actions/checkout@v2
-        with:
-          ref: ${{ matrix.branch }}
-
       - uses: actions/setup-node@v2
       - run: npm install semver
 
@@ -59,6 +55,11 @@ jobs:
               return { version: latestVersion }
             }
 
+      - uses: actions/checkout@v2
+        if: steps.get-latest-release.outputs.result
+        with:
+          ref: ${{ matrix.branch }}
+
       - name: Update stack version
         id: update-files
         if: steps.get-latest-release.outputs.result

.gitignore

@@ -1,3 +0,0 @@
-# Node.js artifacts created by certain GitHub Actions
-/node_modules/
-/package-lock.json