bpo-38693: Prefer f-strings in importlib.resources (importlib_resources 5.0.6). (GH-26387) (#26389)

Automerge-Triggered-By: GH:jaraco
(cherry picked from commit f6fbdb90ee450ad693f7a7809035d0dc968f98b7)

Co-authored-by: Jason R. Coombs <jaraco@jaraco.com>

Co-authored-by: Jason R. Coombs <jaraco@jaraco.com>
diff --git a/Lib/importlib/readers.py b/Lib/importlib/readers.py
index 3e91c1c..41089c0 100644
--- a/Lib/importlib/readers.py
+++ b/Lib/importlib/readers.py
@@ -94,16 +94,15 @@ def joinpath(self, child):
     __truediv__ = joinpath
 
     def open(self, *args, **kwargs):
-        raise FileNotFoundError('{} is not a file'.format(self))
+        raise FileNotFoundError(f'{self} is not a file')
 
     @property
     def name(self):
         return self._paths[0].name
 
     def __repr__(self):
-        return 'MultiplexedPath({})'.format(
-            ', '.join("'{}'".format(path) for path in self._paths)
-        )
+        paths = ', '.join(f"'{path}'" for path in self._paths)
+        return f'MultiplexedPath({paths})'
 
 
 class NamespaceReader(abc.TraversableResources):