[core] auto create release notes with every push on develop (#3985)

and remove CHANGELOG.md logic.

This is my attempt to create a draft release instead of editing a
changelog, see discussion on discord.

Logic:
- new github workflow `.github/workflows/release-notes.yaml`
- runs with every push on `develop` (so after PR's are merged)
- collects the commits on `develop` which are newer than the latest tag
- searches the commit messages for keywords defined in an array and
group the messages into categories (this is a first shot, we will update
this ...)
- creates markdown content
- looks for an untagged and unpublished draft release with name
`unreleased`, if it exists, it will be deleted
- creates an untagged and unpublished draft release with name
`unreleased` with markdown content created above

Example created on my fork (this caused having `MagicMirrorOrg` in the
PR-Links):

<img width="952" height="1804" alt="grafik"
src="https://github.com/user-attachments/assets/38687bed-f5da-4dcb-93eb-242c317769df"
/>

Please review this PR, it is a draft release at the moment because I got
problems in my fork where I tested this: The created draft release is
not visible at the moment (they are visible via api). AFAIS this is a
queue problem on GitHub, maybe I flooded their queue while testing ...
So I will test this tomorrow again before removing `draft` here.

.github/workflows/enforce-pullrequest-rules.yaml

@@ -1,6 +1,5 @@
-# This workflow enforces on every pull request:
-# - the update of our CHANGELOG.md file, see: https://github.com/dangoslen/changelog-enforcer
-# - that the PR is not based against master, taken from https://github.com/oppia/oppia-android/pull/2832/files
+# This workflow enforces on every pull request that the PR is not based against master,
+# taken from https://github.com/oppia/oppia-android/pull/2832/files
 
 name: "Enforce Pull-Request Rules"
 
@@ -13,11 +12,6 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 10
     steps:
-      - name: "Enforce changelog"
-        uses: dangoslen/changelog-enforcer@v3
-        with:
-          changeLogPath: "CHANGELOG.md"
-          skipLabels: "Skip Changelog"
       - name: "Enforce develop branch"
         if: ${{ github.event.pull_request.base.ref == 'master' && !contains(github.event.pull_request.labels.*.name, 'mastermerge') }}
         run: |