replace old %-formatted and .format(…) strings with f-strings (#7671)

mostly using flynt
https://github.com/ikamensh/flynt

gallery_dl/extractor/fapello.py

@@ -29,7 +29,7 @@ class FapelloPostExtractor(Extractor):
         self.model, self.id = match.groups()
 
     def items(self):
-        url = "{}/{}/{}/".format(self.root, self.model, self.id)
+        url = f"{self.root}/{self.model}/{self.id}/"
         page = text.extr(
             self.request(url, allow_redirects=False).text,
             'class="uk-align-center"', "</div>", None)
@@ -66,8 +66,7 @@ class FapelloModelExtractor(Extractor):
         num = 1
         data = {"_extractor": FapelloPostExtractor}
         while True:
-            url = "{}/ajax/model/{}/page-{}/".format(
-                self.root, self.model, num)
+            url = f"{self.root}/ajax/model/{self.model}/page-{num}/"
             page = self.request(url).text
             if not page:
                 return
@@ -109,8 +108,8 @@ class FapelloPathExtractor(Extractor):
                 data = {"_extractor": FapelloModelExtractor}
 
         while True:
-            page = self.request("{}/ajax/{}/page-{}/".format(
-                self.root, self.path, num)).text
+            url = f"{self.root}/ajax/{self.path}/page-{num}/"
+            page = self.request(url).text
             if not page:
                 return