Backport PR #52370 on branch 2.0.x (DOC: Update final date for pandas 2.0 release notes) (#52372)

Backport PR #52370: DOC: Update final date for pandas 2.0 release notes

Co-authored-by: Marc Garcia <[email protected]>

Author: meeseeksmachine

doc/source/whatsnew/v2.0.0.rst

@@ -1,7 +1,7 @@
 .. _whatsnew_200:
 
-What's new in 2.0.0 (March XX, 2023)
-------------------------------------
+What's new in 2.0.0 (April 3, 2023)
+-----------------------------------
 
 These are the changes in pandas 2.0.0. See :ref:`release` for a full changelog
 including other versions of pandas.