message: fix build-auth test
  libgit2 somehow reverted the version back to 0.25.0 after the 0.25.1 release
diff: @@ -34,9 +34,9 @@ fn http_auth_offered() {
  let mut conn = BufStream::new(server.accept().unwrap().0);
  let req = headers(&mut conn);
  let user_agent = if cfg!(windows) {
  - "User-Agent: git/1.0 (libgit2 0.25.1)"
  + "User-Agent: git/1.0 (libgit2 0.25.0)"
  } else {
  - "User-Agent: git/2.0 (libgit2 0.25.1)"
  + "User-Agent: git/2.0 (libgit2 0.25.0)"
  };
  conn.write_all(b"\
  HTTP/1.1 401 Unauthorized\r\n\
  