chore: clean up issue templates (#9355)

.github/ISSUE_TEMPLATE/config.yml

@@ -2,7 +2,7 @@ blank_issues_enabled: false
 contact_links:
   - name: CodeIgniter Forum
     url: https://forum.codeigniter.com/forum-30.html
-    about: Please ask your support questions in the forums. Thanks!
+    about: Please ask your support questions and/or feature requests in the forums. Thanks!
 
   - name: CodeIgniter Slack channel
     url: https://codeigniterchat.slack.com

.github/ISSUE_TEMPLATE/planned-work.md

@@ -1,10 +1,10 @@
 ---
 name: Planned work
-about: Approved work planning
+about: Maintainers' space. DO NOT use this for your bug reports!
 title: 'Dev: '
 labels: dev
 assignees: ''
 
 ---
 
-Repo maintainers will create "issues" for planned work, so it can be tracked.
+Maintainers will create "issues" for planned work, so it can be tracked.

.github/mergeable.yml

@@ -0,0 +1,41 @@
+# https://mergeable.readthedocs.io/en/latest/configuration.html
+
+version: 2
+mergeable:
+  - when: issues.opened
+    validate:
+      - do: description
+        and:
+          - must_include:
+              regex: '^### PHP Version'
+          - must_include:
+              regex: '^### CodeIgniter4 Version'
+      - do: author
+        and:
+          - must_exclude:
+              regex: 'kenjis'
+          - must_exclude:
+              regex: 'lonnieezell'
+          - must_exclude:
+              regex: 'MGatner'
+          - must_exclude:
+              regex: 'michalsn'
+          - must_exclude:
+              regex: 'paulbalandan'
+          - must_exclude:
+              regex: 'samsonasik'
+    fail:
+      - do: comment
+        payload: |
+          Hi there! :wave:
+
+          It looks like you opened an issue without following the bug report template:
+
+          Bug report ([open an issue](https://github.com/codeigniter4/CodeIgniter4/issues/new?assignees=&labels=bug&projects=&template=bug_report.yml&title=Bug%3A+))
+
+          If you are opening a feature request or support question, please do so in the [forums](https://forum.codeigniter.com/forum-30.html).
+
+          The current issue will be closed. This is a precaution to save maintainers' time, I hope you'll understand.
+
+          Sincerely, the mergeable bot 🤖
+      - do: close