Fix: unknown type name ‘my_bool’; did you mean ‘_Bool’?

See: brianmario/mysql2#980

Error messages:

Fetching mysql2 0.3.21
Installing mysql2 0.3.21 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

...

compiling client.c
client.c: In function ‘nogvl_read_query_result’:
client.c:439:3: error: unknown type name ‘my_bool’; did you mean ‘_Bool’?
  439 |   my_bool res = mysql_read_query_result(client);
      |   ^~~~~~~
      |   _Bool
client.c: In function ‘rb_query’:

gemfiles/4.2.gemfile

@@ -3,7 +3,7 @@ source 'https://rubygems.org'
 gem 'activerecord', '~> 4.2.0'
 
 group :test do
-  gem 'mysql2', '0.3.21' if %w[mysql makara_mysql].include?(ENV['DB'])
+  gem 'mysql2', '0.4.10' if %w[mysql makara_mysql].include?(ENV['DB'])
   gem 'pg', '~> 0.18' if %w[pg makara_pg].include?(ENV['DB'])
   gem 'makara', '~> 0.4.1' if %w[makara_mysql makara_pg].include?(ENV['DB'])
   gem 'simplecov', '< 0.18'

gemfiles/5.0.gemfile

@@ -3,7 +3,7 @@ source 'https://rubygems.org'
 gem 'activerecord', '~> 5.0.0'
 
 group :test do
-  gem 'mysql2', '0.3.21' if %w[mysql makara_mysql].include?(ENV['DB'])
+  gem 'mysql2', '0.4.10' if %w[mysql makara_mysql].include?(ENV['DB'])
   gem 'pg', '~> 0.18' if %w[pg makara_pg].include?(ENV['DB'])
   gem 'makara', '~> 0.4.1' if %w[makara_mysql makara_pg].include?(ENV['DB'])
   gem 'simplecov', '< 0.18'

gemfiles/5.1.gemfile

@@ -3,7 +3,7 @@ source 'https://rubygems.org'
 gem 'activerecord', '~> 5.1.0'
 
 group :test do
-  gem 'mysql2', '0.3.21' if %w[mysql makara_mysql].include?(ENV['DB'])
+  gem 'mysql2', '0.4.10' if %w[mysql makara_mysql].include?(ENV['DB'])
   gem 'pg', '~> 0.18' if %w[pg makara_pg].include?(ENV['DB'])
   gem 'makara', '~> 0.4.1' if %w[makara_mysql makara_pg].include?(ENV['DB'])
   gem 'simplecov', '< 0.18'