Fix metrics workflow to use deploy key

.github/workflows/metrics.yaml

@@ -140,11 +140,12 @@ jobs:
 
       - name: Combine json
         run: |
-          git clone --depth 1 https://$METRICS_TOKEN@github.com/rust-analyzer/metrics.git
+          echo "${{ secrets.METRICS_DEPLOY_KEY }}" > ~/.ssh/id_ed25519
+          chmod 600 ~/.ssh/id_ed25519
+
+          git clone --depth 1 git@github.com/rust-analyzer/metrics.git
           jq -s ".[0] * .[1] * .[2] * .[3] * .[4] * .[5]" build.json self.json ripgrep-13.0.0.json webrender-2022.json diesel-1.4.8.json hyper-0.14.18.json -c >> metrics/metrics.json
           cd metrics
           git add .
           git -c user.name=Bot -c user.email=dummy@example.com commit --message 📈
           git push origin master
-    env:
-      METRICS_TOKEN: ${{ secrets.METRICS_TOKEN }}