Replace contributor-visible mentions of BPO in .github/*

.github/CONTRIBUTING.rst

@@ -44,7 +44,7 @@ comments they leave and their "Details" links, respectively. The key points of
 our workflow that are not covered by a bot or status check are:
 
 - All discussions that are not directly related to the code in the pull request
-  should happen on bugs.python.org
+  should happen on `GitHub Issues <https://github.com/python/cpython/issues>`_.
 - Upon your first non-trivial pull request (which includes documentation changes),
   feel free to add yourself to ``Misc/ACKS``
 

.github/PULL_REQUEST_TEMPLATE.md

@@ -7,10 +7,10 @@ Please read this comment in its entirety. It's quite important.
 It should be in the following format:
 
 ```
-bpo-NNNN: Summary of the changes made
+gh-NNNNN: Summary of the changes made
 ```
 
-Where: bpo-NNNN refers to the issue number in the https://bugs.python.org.
+Where: gh-NNNNN refers to the GitHub issue number.
 
 Most PRs will require an issue number. Trivial changes, like fixing a typo, do not need an issue.
 

.github/workflows/build.yml

@@ -1,6 +1,6 @@
 name: Tests
 
-# bpo-40548: "paths-ignore" is not used to skip documentation-only PRs, because
+# gh-84728: "paths-ignore" is not used to skip documentation-only PRs, because
 # it prevents to mark a job as mandatory. A PR cannot be merged if a job is
 # mandatory but not scheduled because of "paths-ignore".
 on: