built: update lint version to 1.6.0

* test: JsonCacheWrap, JsonCacheMem and JsonCacheFake.

Closes #22

* build: update linter

Author: rafamizes

README.md

@@ -34,6 +34,7 @@ like [sharable_preferences](https://pub.dev/packages/shared_preferences) and
 [local storage](https://pub.dev/packages/localstorage) that unifies them as an
 elegant caching API.
 
+
 **Why Json?**
 
 - Because most of the local storage packages available for Flutter applications

pubspec.lock

@@ -66,7 +66,7 @@ packages:
       name: lint
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.5.3"
+    version: "1.7.2"
   matcher:
     dependency: transitive
     description:
@@ -157,5 +157,5 @@ packages:
     source: hosted
     version: "2.1.0"
 sdks:
-  dart: ">=2.12.0 <3.0.0"
+  dart: ">=2.14.0-360.0.dev <3.0.0"
   flutter: ">=1.17.0"

pubspec.yaml

@@ -16,4 +16,4 @@ dependencies:
 dev_dependencies:
   flutter_test:
     sdk: flutter
-  lint: ^1.5.3
+  lint: ^1.6.0