ci: run label check during merge group

[AustinAbro321]

Description

For some reason the label check is required to be run on merge group push, but doesn't unless specified

Checklist before merging

• Test, docs, adr added or updated as needed
• Contributor Guide Steps followed

[netlify]

✅ Deploy Preview for zarf-docs canceled.

Name	Link
🔨 Latest commit	d9993fd
🔍 Latest deploy log	https://app.netlify.com/sites/zarf-docs/deploys/66841e1fd80e1b000886d162

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 19.04%. Comparing base (a8650d3) to head (d9993fd).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2689   +/-   ##
=======================================
  Coverage   19.04%   19.04%           
=======================================
  Files         170      170           
  Lines       12194    12194           
=======================================
  Hits         2322     2322           
  Misses       9586     9586           
  Partials      286      286           

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