Fix activesupport dependency requirement

[andreslucena]

While working with the gem, I realized that I made a mistake with the activesupport requirement, as I've added it as a development requirement but it's actually also for production usage:

$ grep -r active_support lib/
lib/decidim/maintainers_toolbox/github_manager/poster.rb:require "active_support/core_ext/hash/except"
lib/decidim/maintainers_toolbox/github_manager/querier/by_label.rb:require "active_support/core_ext/time/zones"
lib/decidim/maintainers_toolbox/backports_reporter/cli_report.rb:require "active_support/core_ext/string/filters"

This PR fixes this error. We should do a release after merging this (v0.2.0)

Testing

To check the bug:

Start with a new version of ruby without any gem installed (only the default ones)
Install decidim-maintainers_toolbox gem: gem install decidim-maintainers_toolbox
Try to use the gem
See error

Stacktrace

$ decidim-backports-checker --github-token=(gh auth token) --last-version-number 0.28 --days-to-check-from 10
Traceback (most recent call last):
        8: from /home/apereira/.local/share/mise/installs/ruby/2.7.6/bin/decidim-backports-checker:23:in `<main>'
        7: from /home/apereira/.local/share/mise/installs/ruby/2.7.6/bin/decidim-backports-checker:23:in `load'
        6: from /home/apereira/.local/share/mise/installs/ruby/2.7.6/lib/ruby/gems/2.7.0/gems/decidim-maintainers_toolbox-0.1.0/exe/decidim-backports-checker:6:in `<top (required)>'
        5: from /home/apereira/.local/share/mise/installs/ruby/2.7.6/lib/ruby/gems/2.7.0/gems/decidim-maintainers_toolbox-0.1.0/exe/decidim-backports-checker:6:in `require_relative'
        4: from /home/apereira/.local/share/mise/installs/ruby/2.7.6/lib/ruby/gems/2.7.0/gems/decidim-maintainers_toolbox-0.1.0/lib/decidim/maintainers_toolbox/git_backport_checker.rb:5:in `<top (required)>'
        3: from /home/apereira/.local/share/mise/installs/ruby/2.7.6/lib/ruby/gems/2.7.0/gems/decidim-maintainers_toolbox-0.1.0/lib/decidim/maintainers_toolbox/git_backport_checker.rb:5:in `require_relative'
        2: from /home/apereira/.local/share/mise/installs/ruby/2.7.6/lib/ruby/gems/2.7.0/gems/decidim-maintainers_toolbox-0.1.0/lib/decidim/maintainers_toolbox/github_manager/querier/by_label.rb:3:in `<top (required)>'
        1: from /home/apereira/.local/share/mise/installs/ruby/2.7.6/lib/ruby/2.7.0/rubygems/core_ext/kernel_require.rb:83:in `require'
/home/apereira/.local/share/mise/installs/ruby/2.7.6/lib/ruby/2.7.0/rubygems/core_ext/kernel_require.rb:83:in `require': cannot load such file -- active_support/core_ext/time/zones (LoadError)

[alecslupu]

👍