Updated sdk constraint to 2.5.2

Author: Giorgio

CHANGELOG.md

@@ -5,6 +5,7 @@
 * Fixed problem in SelectorBuilder:
 if you set a raw map, then you couldn't add any new query expression or you loose the inital raw map "query" section.
 * Lint clean-up
+* Updated sdk constraint to 2.5.2
 
 ## 0.4.1
 

pubspec.yaml

@@ -3,7 +3,7 @@ version: 0.4.2
 description: Query builder for mongo_dart and objectory
 homepage: https://github.com/mongo-dart/mongo_dart_query
 environment:
-  sdk: ">=2.0.0-dev.69.0 <3.0.0"
+  sdk: ">=2.5.2 <3.0.0"
 dependencies:
   bson: "^0.3.2"
   meta: ^1.1.7