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

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

gallery_dl/config.py

@@ -155,8 +155,7 @@ def status():
 
         paths.append((path, status))
 
-    fmt = "{{:<{}}} : {{}}\n".format(
-        max(len(p[0]) for p in paths)).format
+    fmt = f"{{:<{max(len(p[0]) for p in paths)}}} : {{}}\n".format
 
     for path, status in paths:
         stdout_write(fmt(path, status))