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

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

gallery_dl/extractor/wikiart.py

@@ -77,13 +77,12 @@ class WikiartArtistExtractor(WikiartExtractor):
         self.artist = None
 
     def metadata(self):
-        url = "{}/{}/{}?json=2".format(self.root, self.lang, self.artist_name)
+        url = f"{self.root}/{self.lang}/{self.artist_name}?json=2"
         self.artist = self.request(url).json()
         return {"artist": self.artist}
 
     def paintings(self):
-        url = "{}/{}/{}/mode/all-paintings".format(
-            self.root, self.lang, self.artist_name)
+        url = f"{self.root}/{self.lang}/{self.artist_name}/mode/all-paintings"
         return self._pagination(url)
 
 
@@ -101,10 +100,8 @@ class WikiartImageExtractor(WikiartArtistExtractor):
         title, sep, year = self.title.rpartition("-")
         if not sep or not year.isdecimal():
             title = self.title
-        url = "{}/{}/Search/{} {}".format(
-            self.root, self.lang,
-            self.artist.get("artistName") or self.artist_name, title,
-        )
+        url = (f"{self.root}/{self.lang}/Search/"
+               f"{self.artist.get('artistName') or self.artist_name} {title}")
         return self._pagination(url, stop=True)
 
 
@@ -124,8 +121,7 @@ class WikiartArtworksExtractor(WikiartExtractor):
         return {"group": self.group, "type": self.type}
 
     def paintings(self):
-        url = "{}/{}/paintings-by-{}/{}".format(
-            self.root, self.lang, self.group, self.type)
+        url = f"{self.root}/{self.lang}/paintings-by-{self.group}/{self.type}"
         return self._pagination(url)
 
 
@@ -141,8 +137,7 @@ class WikiartArtistsExtractor(WikiartExtractor):
         self.type = match[3]
 
     def items(self):
-        url = "{}/{}/App/Search/Artists-by-{}".format(
-            self.root, self.lang, self.group)
+        url = f"{self.root}/{self.lang}/App/Search/Artists-by-{self.group}"
         params = {"json": "3", "searchterm": self.type}
 
         for artist in self._pagination(url, params, "Artists"):