Issue #14043: Speed up importlib's _FileFinder by at least 8x, and add a new importlib.invalidate_caches() function.

importlib is now often faster than imp.find_module() at finding modules.
diff --git a/Misc/NEWS b/Misc/NEWS
index 61b4035..5c24b99 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -469,6 +469,9 @@
 Library
 -------
 
+- Issue #14043: Speed up importlib's _FileFinder by at least 8x, and add a
+  new importlib.invalidate_caches() function.
+
 - Issue #14001: CVE-2012-0845: xmlrpc: Fix an endless loop in
   SimpleXMLRPCServer upon malformed POST request.