Added Lyrics w. Timestamps

Added `get_lyrics_with_timestamps` to get lyrics with timestamps.
The Method doesn't try to parse the response as normal lyrics, if no lyrics with timestamps are returned. (could be changed to do so tho, the format is the same)

ytmusicapi/mixins/browsing.py

@@ -865,6 +865,65 @@ def get_lyrics(self, browseId: str) -> dict:
 
         return lyrics
 
+        def get_lyrics_with_timestamps(self, browseId: str) -> dict:
+        """
+        Returns lyrics of a song with timestamps, if available.
+        If no timestaps are given, this method won't replicate the behavior of `get_lyrics`!
+
+        :param browseId: Lyrics browse id obtained from `get_watch_playlist` (startswith `MPLYt`)
+        :return: Dictionary with song lyrics.
+
+        Example::
+
+            {
+                "lyrics": [
+                    {
+                        "lyricLine": "I was a liar",
+                        "cueRange": {
+                            "startTimeMilliseconds": "9200",
+                            "endTimeMilliseconds": "10630",
+                            "metadata": {
+                                "id": "1"
+                            }
+                        }
+                    },
+                    {
+                        "lyricLine": "I gave in to the fire",
+                        "cueRange": {
+                            "startTimeMilliseconds": "10680",
+                            "endTimeMilliseconds": "12540",
+                            "metadata": {
+                                "id": "2"
+                            }
+                        }
+                    },
+                ],
+                "source": "Source: LyricFind"
+            }
+
+        """
+        lyrics = {}
+        if not browseId:
+            raise YTMusicUserError(
+                "Invalid browseId provided. This song might not have lyrics.")
+
+        # change the Client to get lyrics with timestamps (mobile only)
+        copied_context_client = self.context["context"]["client"].copy()
+        self.context["context"]["client"].update({
+            "clientName": "ANDROID_MUSIC",
+            "clientVersion": "7.21.50"
+        })
+        response = self._send_request("browse", {"browseId": browseId})
+        # restore the old context
+        self.context["context"]["client"] = copied_context_client
+
+        base_path = ["contents", "elementRenderer", "newElement", "type", 
+                     "componentType", "model", "timedLyricsModel", "lyricsData"]
+        lyrics["lyrics"] = nav(response, [*base_path, "timedLyricsData"], True)
+        lyrics["source"] = nav(response, [*base_path, "sourceMessage"], True)
+
+        return lyrics
+
     def get_basejs_url(self):
         """
         Extract the URL for the `base.js` script from YouTube Music.