chore: Update PR template, add cut-off marker (acts-project#3741)

Kodiak handles this

Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>

.github/pull_request_template.md

@@ -1,41 +1,7 @@
-PLEASE FOLLOW THE CHECKLIST BELOW WHEN CREATING A NEW PULL REQUEST. THE
-CHECKLIST IS FOR YOUR INFORMATION AND MUST BE REMOVED BEFORE SUBMITTING THE PULL
-REQUEST.
+PLEASE DESCRIBE YOUR CHANGES.
+THIS MESSAGE ENDS UP AS THE COMMIT MESSAGE.
+DO NOT USE @-MENTIONS HERE!
 
-## Checklist
+--- END COMMIT MESSAGE ---
 
-- [ ] Does the PR title follow the `<prefix>: title` scheme?
-
-    The prefix must be one of:
-
-  - `fix`: for a bugfix
-  - `feat`: for a new feature
-  - `refactor`: for an improvement of an existing feature
-  - `perf`, `test`: for performance- or test-related changes
-  - `docs`: for documentation-related changes
-  - `build`, `ci`, `chore`: as appropriated for infrastructure changes
-
-- [ ] Does this modify the public API as defined in `docs/versioning.rst`?
-
-  - [ ] Does the PR title contain a `!` to indicate a breaking change?
-  - [ ] Is there section starting with `BREAKING CHANGE:` in the PR body
-          that explains the breaking change?
-
-- [ ] Is the PR ready to be merged?
-
-  - [ ] If not: is it marked as a draft PR?
-
-- [ ] Does this PR close an existing issue?
-
-  - [ ] Is the issue correctly linked so it will be automatically closed
-        upon successful merge (See closing keywords link in the sidebar)?
-
-- The CI will initially report a missing milestone. One of the maintainers will
-  handle assigning a milestone for book-keeping.
-
-- An automated workflow will assign labels based on changed files, and whether
-  or not reference files were changed. These do not have to be set manually.
-
-- If you push updates, and you know they will be superseded later on, consider adding
-  `[skip ci]` in the commit message. This will instruct the CI system not to run any
-  jobs on this commit.
+Any further description goes here, @-mentions are ok here!

.kodiak.toml

@@ -2,7 +2,7 @@ version = 1
 
 merge.message.title = "pull_request_title"
 merge.message.body = "pull_request_body"
-merge.message.cut_body_before = "--- BEGIN COMMIT MESSAGE ---"
+merge.message.cut_body_after = "--- END COMMIT MESSAGE ---"
 merge.message.cut_body_and_text = true
 merge.method = "squash"
 merge.message.include_coauthors = true