Backport PR #39681: DOC: update release date for 1.2.2 (#39682)

Co-authored-by: Simon Hawkins <[email protected]>

Author: meeseeksmachine

doc/source/whatsnew/v1.2.2.rst

@@ -1,6 +1,6 @@
 .. _whatsnew_122:
 
-What's new in 1.2.2 (February 08, 2021)
+What's new in 1.2.2 (February 09, 2021)
 ---------------------------------------
 
 These are the changes in pandas 1.2.2. See :ref:`release` for a full changelog