Bump mysql2 from 0.4.10 to 0.5.2

Bumps [mysql2](https://github.com/brianmario/mysql2) from 0.4.10 to 0.5.2.
- [Release notes](https://github.com/brianmario/mysql2/releases)
- [Changelog](https://github.com/brianmario/mysql2/blob/master/CHANGELOG.md)
- [Commits](https://github.com/brianmario/mysql2/compare/0.4.10...0.5.2)

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

Gemfile

@@ -23,7 +23,7 @@ gem 'jquery-ui-rails' , '~>5.0.5'
 # always possible on all platforms
 # Alternatively use --without <group> arguments to bundler to not install that group
 gem "sqlite3", group: :sqlite
-gem "mysql2", "~> 0.4.0", group: :mysql
+gem "mysql2", "~> 0.5.2", group: :mysql
 
 gem "RedCloth"
 gem "sanitize", ">=3.0.0"

Gemfile.lock

@@ -130,7 +130,7 @@ GEM
     minitest-stub-const (0.6)
     mocha (1.7.0)
       metaclass (~> 0.0.1)
-    mysql2 (0.4.10)
+    mysql2 (0.5.2)
     nio4r (2.3.1)
     nokogiri (1.8.5)
       mini_portile2 (~> 2.3.0)
@@ -290,7 +290,7 @@ DEPENDENCIES
   listen
   minitest-stub-const
   mocha
-  mysql2 (~> 0.4.0)
+  mysql2 (~> 0.5.2)
   paperclip
   puma (~> 3.0)
   rack-mini-profiler