Update to crystal-db ~> 0.7.0 (#44)

Author: Brian J. Cardiff

shard.yml

@@ -4,7 +4,7 @@ version: 0.13.0
 dependencies:
   db:
     github: crystal-lang/crystal-db
-    version: ~> 0.6.0
+    version: ~> 0.7.0
 
 authors:
   - Ary Borenszweig <[email protected]>