Upgrade upload-artifact action to version 4

Author: shuzijun

.github/workflows/snapshot.yml

@@ -45,7 +45,7 @@ jobs:
     #    cat ${{steps.verify.outputs.verification-output-log-filename}}
 
     - name: Upload Artifact
-      uses: actions/upload-artifact@v2
+      uses: actions/upload-artifact@v4
       with:
         # TODO: This uploads a zip called `distributions`; see what we can do to just upload the produced plugin itself.
         name: leetcode-editor-snapshot