Automatically update Dependabot pull requests

[Mrtenz]

This updates the "update PR" workflow to trigger for Dependabot PRs automatically.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.88%. Comparing base (58f0079) to head (1057c83).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3064   +/-   ##
=======================================
  Coverage   94.88%   94.88%           
=======================================
  Files         506      506           
  Lines       11124    11124           
  Branches     1703     1703           
=======================================
  Hits        10555    10555           
  Misses        569      569           

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[FrederikBolding]

Where is this used?

[Mrtenz]

Mainly as token for actions/checkout@v4:

snaps/.github/workflows/update-pull-request.yml

Lines 196 to 198 in 1057c83

	# Use PAT to ensure that the commit later can trigger status check
	# workflows.
	token: ${{ secrets.PULL_REQUEST_UPDATE_TOKEN }}