🐺 Fix net_unittests on Android swarming by adding testserver as a data_dep

net/tools/testserver/BUILD.gn

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-group("isolate_py") {
-  _py_files =
-      read_file("//build/secondary/tools/swarming_client/isolate.pydeps",
-                "list lines")
+group("testserver_py") {
+  _py_files = read_file("testserver.pydeps", "list lines")
 
   # Filter out comments.
   set_sources_assignment_filter([ "#*" ])
   sources = _py_files
   data = sources
 }