Update our RTD redirects to use latest for dev, stable for errors

Author: pradyunsg

.readthedocs-custom-redirects.yml

@@ -2,9 +2,9 @@
 # It is related to Read the Docs, but is not a file processed by the platform.
 
 /dev/news-entry-failure: >-
-  https://pip.pypa.io/en/stable/development/contributing/#news-entries
+  https://pip.pypa.io/en/latest/development/contributing/#news-entries
 /errors/resolution-impossible: >-
-  https://pip.pypa.io/en/latest/topics/dependency-resolution/#dealing-with-dependency-conflicts
+  https://pip.pypa.io/en/stable/topics/dependency-resolution/#dealing-with-dependency-conflicts
 /surveys/backtracking: >-
   https://forms.gle/LkZP95S4CfqBAU1N6
 /warnings/backtracking: >-