CI: Update slim_lint version to fix rexml/document (LoadError)

[taketo1113]

This Pull Request has been created because CI raises the error of rexml/document (LoadError) with ruby 3.0 or higher.

For CI error details, see the following:

# CI: Ruby 3.3 - Rails 7.2
$ bundle exec rake
...
/opt/hostedtoolcache/Ruby/3.3.6/x64/lib/ruby/3.3.0/bundled_gems.rb:69:in `require': cannot load such file -- rexml/document (LoadError)
	from /opt/hostedtoolcache/Ruby/3.3.6/x64/lib/ruby/3.3.0/bundled_gems.rb:69:in `block (2 levels) in replace_require'
	from /home/runner/work/slim-rails/slim-rails/vendor/bundle/ruby/3.3.0/gems/zeitwerk-2.7.1/lib/zeitwerk/core_ext/kernel.rb:34:in `require'
	from /home/runner/work/slim-rails/slim-rails/vendor/bundle/ruby/3.3.0/gems/slim_lint-0.24.0/lib/slim_lint/reporter/checkstyle_reporter.rb:3:in `<top (required)>'
...

https://github.com/taketo1113/slim-rails/actions/runs/11685319779/job/32538807815

This Pull Request changes to update slim_lint gem version of v0.29.0 or higher to fix rexml/document (LoadError).
slim_lint v0.29.0 has added a dependency on rexml because RuboCop v1.66.0 dropped its dependency on rexml.
sds/slim-lint#184