Keep Dosh server service alive

tests/release_scripts.rs

@@ -25,6 +25,10 @@ fn systemd_service_does_not_sandbox_remote_shells() {
     let install = include_str!("../install.sh");
     for raw in [service, install] {
         assert!(raw.contains("KillMode=process"));
+        assert!(
+            raw.contains("Restart=always"),
+            "dosh-server should come back after accidental SIGTERM while preserving child shells"
+        );
         for directive in [
             "NoNewPrivileges=",
             "PrivateTmp=",