Change link from NEP 29 to SPEC 0 for Numpy Guidelines (pandas-dev#59017

)

* Change link from NEP 29 to SPEC 0 for Numpy Guidelines

* Update doc/source/development/policies.rst

Co-authored-by: Matthew Roeschke <10647082+mroeschke@users.noreply.github.com>

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Co-authored-by: Matthew Roeschke <10647082+mroeschke@users.noreply.github.com>

doc/source/development/policies.rst

@@ -51,7 +51,7 @@ pandas may change the behavior of experimental features at any time.
 Python support
 ~~~~~~~~~~~~~~
 
-pandas mirrors the `NumPy guidelines for Python support <https://numpy.org/neps/nep-0029-deprecation_policy.html#implementation>`__.
+pandas mirrors the `SPEC 0 guideline for Python support <https://scientific-python.org/specs/spec-0000>`__.
 
 Security policy
 ~~~~~~~~~~~~~~~