test: Use threaded server in tests

Signed-off-by: Dmitry Dygalo <dmitry@dygalo.dev>

Author: Stranger6667

css-inline/tests/server.py

@@ -1,4 +1,4 @@
-from http.server import HTTPServer, BaseHTTPRequestHandler
+from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
 
 
 class Handler(BaseHTTPRequestHandler):
@@ -17,5 +17,5 @@ def log_message(self, format, *args):
 
 
 if __name__ == "__main__":
-    server = HTTPServer(("0.0.0.0", 1234), Handler)
+    server = ThreadingHTTPServer(("127.0.0.1", 1234), Handler)
     server.serve_forever()