Fix error preventing activity log diff

[crowesn]

Resolves #410

@version.changeset was returning an empty hash due to YAML serialization permitted class exceptions, restrictions introduced after an RCE escalation risk was discovered. Examining the deserializer in the paper_trail gem showed that we needed to allow ActiveSupport::TimeWithZone, Time, ActiveSupport::TimeZone classes for the changes to load.

Debug here: https://github.com/paper-trail-gem/paper_trail/blob/master/lib/paper_trail/version_concern.rb#L357

Related: https://discuss.rubyonrails.org/t/cve-2022-32224-possible-rce-escalation-bug-with-serialized-columns-in-active-record/81017
And: https://stackoverflow.com/a/72970171

Changes

• Allow ActiveSupport::TimeWithZone, Time, ActiveSupport::TimeZone classes for yaml load in config/application.rb
• Add rspec helper class provided by PaperTrail
• Add controller test to activity controller to ensure that diff data is being populated to the changeset
• Add feature test to check for diff strings in activity details show page.
• Upgrade PaperTrail to v.15

Note that PaperTrail/versioning is now turned off for specs by default. To include versioning functionality in specs you need to activate in the test block.

[hortongn]

@crowesn When this PR is ready, please assign it to me and I'll review.

[crowesn]

eh hold of on this for a sec I want to add a controller test for the activity log.

[crowesn]

@hortongn

This should be ready to rock. I added an rpsec helper class packaged with paper trail as well as a controller test to make sure the version changes is populated with diff data.

[hortongn]

@crowesn Nice work on this!