ci(github-actions): set force to true for Homebrew bump formula

[Lee-W]

Description

fix homebrew publishing error as reported #438 (comment)
this solution is suggested by our failed workflow https://github.com/commitizen-tools/commitizen/runs/3845350057?check_suite_focus=true

commitizen 2.20.0 https://github.com/Homebrew/homebrew-core/pull/86905
Duplicate PRs should not be opened. Use --force to override this error.
/usr/local/Homebrew/Library/Homebrew/utils.rb:322:in `safe_system': Failure while executing; `/usr/local/bin/brew bump-formula-pr --no-audit --no-browse --message=\[\`action-homebrew-bump-formula\`\]\(https://github.com/dawidd6/action-homebrew-bump-formula\) --version=2.20.0 --url=https://files.pythonhosted.org/packages/8f/0c/97a94ded248305222b1c5c86c0c58d81c7822e1fa705e92870e9ad643635/commitizen-2.20.0.tar.gz commitizen` exited with 1. (ErrorDuringExecution)
	from /Users/runner/work/_actions/dawidd6/action-homebrew-bump-formula/v3/main.rb:27:in `brew'
	from /Users/runner/work/_actions/dawidd6/action-homebrew-bump-formula/v3/main.rb:112:in `<module:Homebrew>'
	from /Users/runner/work/_actions/dawidd6/action-homebrew-bump-formula/v3/main.rb:18:in `<main>'

according to Homebrew bump formula, this shouldn't break anything

Checklist

• Add test cases to all the changes you introduce
• Run ./script/format and ./script/test locally to ensure this change passes linter check and test
• Test the changes on the local machine manually
• Update the documentation for the changes

Expected behavior

succeeded on homebrew publishing

Steps to Test This Pull Request

Additional context

[codecov]

Codecov Report

Merging #445 (71aabe8) into master (5e22040) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #445   +/-   ##
=======================================
  Coverage   97.37%   97.37%           
=======================================
  Files          39       39           
  Lines        1409     1409           
=======================================
  Hits         1372     1372           
  Misses         37       37           

Flag	Coverage Δ
unittests	97.37% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
commitizen/__version__.py	100.00% <100.00%> (ø)

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