Use setup-ssh action (#7)

Switch to the [setup-ssh](https://github.com/TheHackerApp/setup-ssh)
action to keep behavior consistent across repositories.

Author: akrantz01

action.yml

@@ -40,16 +40,10 @@ runs:
         toolchain: ${{ inputs.toolchain }}
         components: ${{ inputs.components }}
 
-    - uses: webfactory/ssh-agent@v0.9.0
+    - uses: TheHackerApp/setup-ssh@main
       with:
-        ssh-private-key: ${{ inputs.ssh-private-key }}
-
-    - name: Add Shipyard host key to .ssh/known_hosts
-      shell: bash
-      run: |
-        mkdir -p ~/.ssh
-        touch ~/.ssh/known_hosts
-        ssh-keyscan ssh.shipyard.rs >> ~/.ssh/known_hosts
+        private-key: ${{ inputs.ssh-private-key }}
+        host: ssh.shipyard.rs
 
     - name: Login to Shipyard registry
       shell: bash