update mysql-otp to 1.4.0

rebar.config

@@ -1,4 +1,4 @@
 {deps, [
-    {mysql, ".*", {git, "https://github.com/mysql-otp/mysql-otp.git", {tag, "1.3.3"}}},
+    {mysql, ".*", {git, "https://github.com/mysql-otp/mysql-otp.git", {tag, "1.4.0"}}},
     {poolboy, ".*", {git, "https://github.com/devinus/poolboy.git", {tag, "1.5.2"}}}
 ]}.