Fix integration tests with custom inventory.

All inventory hosts to which a connection is actually established
should declare ansible_python_interpreter to avoid interpreter
auto-discovery, as that may select the wrong interpreter.

test/integration/targets/connection_paramiko_ssh/test_connection.inventory

@@ -4,3 +4,4 @@ paramiko_ssh-no-pipelining ansible_ssh_pipelining=false
 [paramiko_ssh:vars]
 ansible_host=localhost
 ansible_connection=paramiko_ssh
+ansible_python_interpreter="{{ ansible_playbook_python }}"