Use one of the default ssh identity file names.

.github/workflows/ci.yml

@@ -78,7 +78,7 @@ jobs:
       - name: Store ssh private key and host key
         run: |
           mkdir ~/.ssh
-          echo "$SSH_KEY" > ~/.ssh/deploy_key
+          echo "$SSH_KEY" > ~/.ssh/id_rsa
           echo "[$SSH_HOST]:$SSH_PORT $SSH_HOST_KEY" > ~/.ssh/known_hosts
           chmod 700 ~/.ssh
           chmod 600 ~/.ssh/*