pythongh-134939: Correct concurrent.interpreters source code link (pythonGH-136564)

(cherry picked from commit 42b251b)

Co-authored-by: Stan Ulbrych <89152624+StanFromIreland@users.noreply.github.com>

Author: StanFromIreland

Doc/library/concurrent.interpreters.rst

@@ -9,7 +9,7 @@
 
 .. versionadded:: 3.14
 
-**Source code:** :source:`Lib/concurrent/interpreters.py`
+**Source code:** :source:`Lib/concurrent/interpreters`
 
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