Run bundler update to fix bundler audit vulnerabilities

[Janell-Huyck]

We had a new bundler audit vulnerability centered around Nokogiri. Upon inspection, we were not requiring Nokogiri directly, but it was a requirement for multiple gems we were using. Running "Bunlde update" fixed that vulnerability.

Also fixes #322

[hortongn]

@Janell-Huyck Some failing mailer specs. A fluke or caused by updated gems?

[Janell-Huyck]

@Janell-Huyck Some failing mailer specs. A fluke or caused by updated gems?

Caused by the gem updates. We were doing a stub_const on our ENV file, and that's now seen as changing a frozen constant. I've modified the tests so that they will be testing the same thing without stubbing, using an around block, like this:

      around do |example|
        original_mail_sender = ENV.fetch('MAIL_SENDER', nil)
        ENV['MAIL_SENDER'] = 'sender@example.com'
        example.run
        ENV['MAIL_SENDER'] = original_mail_sender
      end