Bump truemail from 2.3.4 to 2.4.0

Bumps [truemail](https://github.com/truemail-rb/truemail) from 2.3.4 to 2.4.0.
- [Release notes](https://github.com/truemail-rb/truemail/releases)
- [Changelog](https://github.com/truemail-rb/truemail/blob/master/CHANGELOG.md)
- [Commits](https://github.com/truemail-rb/truemail/compare/v2.3.4...v2.4.0)

Signed-off-by: dependabot[bot] <support@github.com>

Gemfile

@@ -20,7 +20,7 @@ gem 'paper_trail', '~> 12.0'
 gem 'pg',                        '1.2.3'
 # 1.8 is for Rails < 5.0
 gem 'ransack', '~> 2.3'
-gem 'truemail', '~> 2.3' # validates email by regexp, mail server existence and address existence
+gem 'truemail', '~> 2.4' # validates email by regexp, mail server existence and address existence
 gem 'validates_email_format_of', '1.6.3' # validates email against RFC 2822 and RFC 3696
 
 # 0.7.3 is the latest for Rails 4.2, however, it is absent on Rubygems server

Gemfile.lock

@@ -461,7 +461,7 @@ GEM
     thor (1.1.0)
     thread_safe (0.3.6)
     tilt (2.0.10)
-    truemail (2.3.4)
+    truemail (2.4.0)
       simpleidn (~> 0.2.1)
     tzinfo (1.2.9)
       thread_safe (~> 0.1)
@@ -568,7 +568,7 @@ DEPENDENCIES
   sidekiq
   simplecov (= 0.17.1)
   simpleidn (= 0.2.1)
-  truemail (~> 2.3)
+  truemail (~> 2.4)
   uglifier
   validates_email_format_of (= 1.6.3)
   webdrivers