Importlib's documentation said that importlib.abc.PyLoader inherited from
importlib.abc.ResourceLoader, when in fact it did not. Fixed the ABC to inherit
as documented.

This doesn't introduce an backwards-incompatiblity as the code in PyLoader
already required the single method ResourceLoader defined as an abstract
method.
diff --git a/Misc/NEWS b/Misc/NEWS
index 4b94ede..9fa8e96 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -43,6 +43,10 @@
 Library
 -------
 
+- importlib.abc.PyLoader did not inherit from importlib.abc.ResourceLoader like
+  the documentation said it did even though the code in PyLoader relied on the
+  abstract method required by ResourceLoader.
+
 - Issue #6431: Make Fraction type return NotImplemented when it doesn't
   know how to handle a comparison without loss of precision.  Also add
   correct handling of infinities and nans for comparisons with float.