build: Move test files to the tests/ directory

We don’t want these to install by default.

examples/test_client.py

@@ -20,6 +20,7 @@ async def main():
         print(msg)
 
 
-loop = get_event_loop()
-loop.run_until_complete(main())
-loop.close()
+if __name__ == "__main__":
+    loop = get_event_loop()
+    loop.run_until_complete(main())
+    loop.close()

examples/test_server.py

@@ -23,7 +23,8 @@ async def main():
     await server.listen()
 
 
-loop = get_event_loop()
-loop.run_until_complete(main())
-loop.run_forever()
-loop.close()
+if __name__ == "__main__":
+    loop = get_event_loop()
+    loop.run_until_complete(main())
+    loop.run_forever()
+    loop.close()