get_playlist: join multiple title runs

* Return complete titles when split on time-like strings:

```diff
>>> yt.get_playlist("PLaZPMsuQNCsWn0iVMtGbaUXO6z-EdZaZm")["title"]
-03 Jan
+03 Jan 12:09
```

* `test_get_playlist`: assert more props have the expected value/shape

tests/mixins/test_playlists.py

@@ -13,25 +13,28 @@
 
 class TestPlaylists:
     @pytest.mark.parametrize(
-        ("test_file", "owned"),
+        "test_file",
         [
-            ("2024_03_get_playlist.json", True),
-            ("2024_03_get_playlist_public.json", False),
-            ("2024_07_get_playlist_collaborative.json", True),
+            "2024_03_get_playlist.json",
+            "2024_03_get_playlist_public.json",
+            "2024_07_get_playlist_collaborative.json",
         ],
     )
-    def test_get_playlist_2024(self, yt, test_file, owned):
-        with open(Path(__file__).parent.parent / "data" / test_file, encoding="utf8") as f:
+    def test_get_playlist(self, yt, test_file):
+        data_dir = Path(__file__).parent.parent / "data"
+        with open(data_dir / test_file, encoding="utf8") as f:
             mock_response = json.load(f)
+        with open(data_dir / "expected_output" / test_file, encoding="utf8") as f:
+            expected_output = json.load(f)
+
         with mock.patch("ytmusicapi.YTMusic._send_request", return_value=mock_response):
             playlist = yt.get_playlist("MPREabc")
-            assert playlist["year"] == "2024"
-            assert playlist["owned"] == owned
-            assert "hours" in playlist["duration"] or "minutes" in playlist["duration"]
-            assert playlist["id"]
-            assert isinstance(playlist["description"], str) and playlist["description"]
-            assert len(playlist["tracks"]) > 0
+            assert playlist == playlist | expected_output
 
+            for thumbnail in playlist.get("thumbnails", []):
+                assert thumbnail["url"] and thumbnail["width"] and thumbnail["height"]
+
+            assert len(playlist["tracks"]) > 0
             for track in playlist["tracks"]:
                 assert isinstance(track["title"], str) and track["title"]
 

ytmusicapi/parsers/playlists.py

@@ -40,7 +40,7 @@ def parse_playlist_header_meta(header: dict[str, Any]) -> dict[str, Any]:
         "views": None,
         "duration": None,
         "trackCount": None,
-        "title": nav(header, TITLE_TEXT, none_if_absent=True),
+        "title": "".join([run["text"] for run in header.get("title", {}).get("runs", [])]),
         "thumbnails": nav(header, THUMBNAILS),
     }
     if "runs" in header["secondSubtitle"]: