Merge pull request #20 from crystal-garage/crystal-pg-0.27.0

use crystal-pg 0.27.0

Author: mamantoha

shard.yml

@@ -18,7 +18,7 @@ dependencies:
     branch: master
   pg:
     github: will/crystal-pg
-    version: "~> 0.26.0"
+    version: "~> 0.27.0"
   inflector:
     github: phoffer/inflector.cr
     version: ">= 0.1.8"