Bump mail from 2.7.1 to 2.8.1

Bumps [mail](https://github.com/mikel/mail) from 2.7.1 to 2.8.1. - [Changelog](https://github.com/mikel/mail/blob/2.8.1/CHANGELOG.rdoc) - [Commits](mikel/mail@2.7.1...2.8.1) --- updated-dependencies: - dependency-name: mail dependency-type: direct:production update-type: version-update:semver-minor ... Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

Gemfile.lock

@@ -193,8 +193,11 @@ GEM
  loofah (2.21.3)
  crass (~> 1.0.2)
  nokogiri (>= 1.12.0)
- mail (2.7.1)
+ mail (2.8.1)
  mini_mime (>= 0.1.1)
+ net-imap
+ net-pop
+ net-smtp
  maildown (3.3.1)
  actionmailer (>= 4.0.0)
  kramdown-parser-gfm
@@ -206,7 +209,7 @@ GEM
  mime-types-data (~> 3.2015)
  mime-types-data (3.2019.1009)
  mini_histogram (0.3.1)
- mini_mime (1.1.2)
+ mini_mime (1.1.5)
  mini_portile2 (2.8.2)
  minitest (5.18.1)
  mocha (1.16.0)