Update version constraints

Author: vinkla

composer.json

@@ -21,10 +21,10 @@
     },
     "require-dev": {
         "orchestra/testbench": "3.1.*",
-        "phpunit/phpunit": "~4.0",
-        "phpspec/phpspec": "~2.0",
-        "mockery/mockery": "~0.9",
-        "henrikbjorn/phpspec-code-coverage": "~1.0"
+        "phpunit/phpunit": "^4.7.6",
+        "phpspec/phpspec": "^2.2.1",
+        "mockery/mockery": "^0.9.4",
+        "henrikbjorn/phpspec-code-coverage": "^1.0.1"
     },
     "autoload": {
         "psr-4": {