Add failing test for caching_sha2_password auth

Reproduction for #26

contrib/ruby/test/client_test.rb

@@ -30,6 +30,13 @@ def test_trilogy_connect_with_native_password_auth_switch
     ensure_closed client
   end
 
+  def test_trilogy_connect_with_caching_sha2_password_auth_switch
+    client = new_tcp_client username: "caching_sha2", password: "password"
+    refute_nil client
+  ensure
+    ensure_closed client
+  end
+
   def test_trilogy_connect_tcp_fixnum_port
     assert_raises TypeError do
       new_tcp_client port: "13306"

docker-entrypoint-initdb.d/caching_sha2_password_user.sql

@@ -0,0 +1,3 @@
+CREATE USER 'caching_sha2'@'%';
+GRANT ALL PRIVILEGES ON test.* TO 'caching_sha2'@'%';
+ALTER USER 'caching_sha2'@'%' IDENTIFIED WITH caching_sha2_password BY 'password';