ci: run SSH tests only on push event

Secrets can't be fetched for security reasons, so we run the SSH tests
only when a new push is performed.

Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>

Author: acerv

.github/workflows/test_ssh.yml

@@ -1,7 +1,7 @@
 # Copyright (c) 2025 Andrea Cervesato <andrea.cervesato@suse.com>
 
 name: "Test SSH"
-on: [push, pull_request]
+on: push
 
 env:
   PYTHON_PKGS: pytest<8.3.5 pytest-asyncio<1.0 build asyncssh