test(server): align tls test with from_files Option<&Path> signature

TlsAcceptor::from_files now accepts the client CA path as Option<&Path>
(per the require_client_auth refactor on main). Wrap the helper's CA
path in Some(...) so the new plaintext-service-http tests compile after
rebasing onto current main.

Author: TaylorMutch

crates/openshell-server/src/lib.rs

@@ -793,7 +793,7 @@ mod tests {
         let acceptor = TlsAcceptor::from_files(
             &dir.path().join("server-cert.pem"),
             &dir.path().join("server-key.pem"),
-            &dir.path().join("ca.pem"),
+            Some(&dir.path().join("ca.pem")),
             false,
         )
         .expect("failed to build tls acceptor");