chore(docs): centralise changelog entries for open versions

Pull requests for user-visible changes each adding a bullet to the unreleased
version's changelog file conflict on every merge. CONTRIBUTING.md now says the
maintainer writes those entries centrally, and that such PRs leave the file out
of the diff. The PR template's changelog box and the generator that annotates
it follow the same rule.

Refs #2449

Author: JarryShaw

.github/PULL_REQUEST_TEMPLATE.md

@@ -7,7 +7,7 @@
 - [ ] [Searched](https://github.com/JarryShaw/PyPCAPKit/pulls?q=is%3Apr) for similar pull requests
 - [ ] Followed the [coding style](https://github.com/JarryShaw/PyPCAPKit/blob/main/CONTRIBUTING.md#coding-style) (`make pylint`, `make mypy`, `make isort`)
 - [ ] `make test` passes, and a test case covers the change
-- [ ] Added a [changelog entry](https://github.com/JarryShaw/PyPCAPKit/blob/main/CONTRIBUTING.md#changelog-entries) under `docs/source/changelog/` and regenerated `CHANGELOG.md`, if the change is user-visible
+- [ ] Described the user-visible change above and left its [changelog entry](https://github.com/JarryShaw/PyPCAPKit/blob/main/CONTRIBUTING.md#changelog-entries) to the maintainer, keeping `docs/source/changelog/` and `CHANGELOG.md` out of the diff, if the change is user-visible
 
 ### What is the purpose of your *pull request*?
 

CONTRIBUTING.md

@@ -25,7 +25,8 @@ A rough outline:
 - Create a topic branch, usually from `main`.
 - Make commits of logical units, and add a test case if the change fixes a bug or adds functionality.
 - Run the tests and make sure they pass (see below).
-- Add a changelog entry if the change is user-visible (see below).
+- If the change is user-visible, describe it in the pull request and leave its changelog entry to
+  the maintainer (see below).
 - Make sure your commit messages are in the proper format (see below).
 - Push your changes to a topic branch in your fork of the repository.
 - Submit a pull request to the repo.
@@ -58,10 +59,15 @@ shapes of it at collection time and say what to do; `tests/_tiers.py` has the re
 Entries live in `docs/source/changelog/<version>.rst`, one file per version, listed newest-first in
 the toctree of `docs/source/changelog.rst`. That tree is the single source of the project's history.
 
+**Pull requests for user-visible changes do not add their own bullet.** While a version is
+unreleased, its entry is written centrally by the maintainer once a change is ready to merge or has
+merged. Feature branches that each edit the same file conflict on every merge, so leave
+`docs/source/changelog/<version>.rst` and `CHANGELOG.md` out of the diff.
+
 **`CHANGELOG.md` is generated — never edit it by hand.** `util/changelog_md.py` derives it from the
 newest entry alone, because its consumers (the `Create Release` workflow's release body and the
-source distribution) read Markdown rather than reStructuredText. Add your bullet to the `.rst`
-entry, then regenerate:
+source distribution) read Markdown rather than reStructuredText. The maintainer adds the bullet to the
+`.rst` entry, then regenerates:
 
 ```shell
 python util/changelog_md.py            # rewrite CHANGELOG.md from the newest entry

tests/project/test_python_versions_update_1660.py

@@ -876,7 +876,9 @@ def test_the_body_lists_what_the_owner_does_by_hand(self) -> None:
         body = module.fill_template((ROOT / module.TEMPLATE).read_text(encoding='utf-8'), description, 'failure')
         self.assertIn('- [x] `ci` — workflows or build tooling', body)
         self.assertEqual(body.count('- [x]'), 1)
-        self.assertIn('regenerated `CHANGELOG.md`, if the change is user-visible — N/A — centralised in #657', body)
+        self.assertIn('- [ ] Described the user-visible change above and left its [changelog entry]', body)
+        self.assertIn('keeping `docs/source/changelog/` and `CHANGELOG.md` out of the diff, '
+                      'if the change is user-visible — N/A — centralised in #657', body)
         self.assertIn('### Description of your *pull request* and other information', body)
         self.assertNotIn('  Explanation of your', body)
         self.assertIn(f'| `3.11` | supported | KTLO | {plan["changes"][0]["reason"]} |', body)

util/update_python_versions.py

@@ -1298,7 +1298,7 @@ def fill_template(template: 'str', description: 'str', audit_outcome: 'str') ->
     text = re.sub(r'(?m)^- \[ \] `ci`', '- [x] `ci`', template)
     audit = {'success': 'passed', 'failure': 'failed'}.get(audit_outcome, audit_outcome)
     text = re.sub(r'(?m)^(- \[ \] `make test` passes.*)$', rf'\1 -- not run; the audit {audit} (below)', text)
-    text = re.sub(r'(?m)^(- \[ \] Added a \[changelog entry\].*)$', r'\1 — N/A — centralised in #657', text)
+    text = re.sub(r'(?m)^(- \[ \] Described the user-visible change.*)$', r'\1 — N/A — centralised in #657', text)
     placeholder = re.search(r'(?m)^  Explanation of your \*pull request\*.*$', text)
     if placeholder is None:
         return text.rstrip('\n') + '\n\n' + description + '\n'