DNM: TEST: feat: improve merge-check action to leave a comment and label to PRs

[UdjinM6]

Please remove the italicized help prompts before submitting or merging

Provide a general summary of your changes in the Title above

Pull requests without a rationale and clear improvement may be closed
immediately.

Please provide clear motivation for your patch and explain how it improves
Dash Core user experience or Dash Core developer experience
significantly:

• Any test improvements or new tests that improve coverage are always welcome.
• All other changes should have accompanying unit tests (see src/test/) or
  functional tests (see test/). Contributors should note which tests cover
  modified code. If no tests exist for a region of modified code, new tests
  should accompany the change.
• Bug fixes are most welcome when they come with steps to reproduce or an
  explanation of the potential issue as well as reasoning for the way the bug
  was fixed.
• Features are welcome, but might be rejected due to design or scope issues.
  If a feature is based on a lot of dependencies, contributors should first
  consider building the system outside of Dash Core, if possible.

Issue being fixed or feature implemented

• Why is this change required? What problem does it solve?
• If it fixes an open issue, please link to the issue here.

What was done?

Describe your changes in detail

How Has This Been Tested?

Please describe in detail how you tested your changes.

Include details of your testing environment, and the tests you ran
to see how your change affects other areas of the code, etc.

Breaking Changes

Please describe any breaking changes your code introduces

Checklist:

Go over all the following points, and put an x in all the boxes that apply.

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated relevant unit/integration/functional/e2e tests
• I have made corresponding changes to the documentation
• I have assigned this pull request to a milestone (for repository code-owners and collaborators only)