Only warn about no content-type if there is a response body

src/surykatka/bot.py

@@ -719,12 +719,20 @@ class WebBot:
                     if (
                         "Content-Type"
                         not in network_change["http_header_dict"]
+                    ):
+                        if (
+                            network_change["http_header_dict"].get(
+                                "Content-Length", 0
+                            )
+                            != 0
                         ):
                             result_dict["warning"].append(
                                 {
                                     "text": "(No Content-Type header) %s"
                                     % (network_change["url"],),
-                                "date": result_dict["bot_status"][0]["date"],
+                                    "date": result_dict["bot_status"][0][
+                                        "date"
+                                    ],
                                 }
                             )
                     elif network_change["http_header_dict"][