replace more '.format(…)' calls with f-strings (#7671)

gallery_dl/extractor/pixnet.py

@@ -19,11 +19,10 @@ class PixnetExtractor(Extractor):
     category = "pixnet"
     filename_fmt = "{num:>03}_{id}.{extension}"
     archive_fmt = "{id}"
-    url_fmt = ""
 
     def __init__(self, match):
         Extractor.__init__(self, match)
-        self.blog, self.item_id = match.groups()
+        self.blog, self.item_id = self.groups
         self.root = f"https://{self.blog}.pixnet.net"
 
     def items(self):
@@ -91,14 +90,13 @@ class PixnetImageExtractor(PixnetExtractor):
 class PixnetSetExtractor(PixnetExtractor):
     """Extractor for images from a pixnet set"""
     subcategory = "set"
-    url_fmt = "{}/album/set/{}"
     directory_fmt = ("{category}", "{blog}",
                      "{folder_id} {folder_title}", "{set_id} {set_title}")
     pattern = BASE_PATTERN + r"/album/set/(\d+)"
     example = "https://USER.pixnet.net/album/set/12345"
 
     def items(self):
-        url = self.url_fmt.format(self.root, self.item_id)
+        url = f"{self.root}/album/set/{self.item_id}"
         page = self.request(url, encoding="utf-8").text
         data = self.metadata(page)