Refactor Dependabot rebase workflow

[nev21]

Updated workflow to rebase Dependabot PRs using GitHub CLI.

[Copilot]

Pull request overview

This PR refactors the Dependabot force rebase workflow from using the peter-evans/rebase@v2 action to a custom implementation using GitHub CLI. Instead of directly rebasing PRs, the new approach posts @dependabot rebase comments on Dependabot PRs to trigger Dependabot's built-in rebase functionality.

Key Changes:

• Replaced the peter-evans/rebase action with a custom bash script that uses GitHub CLI to comment on Dependabot PRs
• Reduced permissions from contents: write + pull-requests: write to only pull-requests: write
• Added checkout step and GitHub CLI installation step

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.17%. Comparing base (aed652d) to head (4166791).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #403      +/-   ##
==========================================
+ Coverage   99.03%   99.17%   +0.13%     
==========================================
  Files          19       19              
  Lines         727      727              
  Branches      183      183              
==========================================
+ Hits          720      721       +1     
+ Misses          7        6       -1     

see 1 file with indirect coverage changes

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