Updated some of the development dependancies

Author: David Yell

composer.json

@@ -17,14 +17,14 @@
  "source": "https://github.com/davidyell/CakePHP3-Proffer"
 },
 "require": {
-"php": ">=5.6",
+"php": ">=5.6.0",
 "cakephp/orm": "3.*",
 "intervention/image": "^2.3"
 },
  "require-dev": {
- "phpunit/phpunit": "^5.5",
- "cakephp/cakephp": "^3.4.0",
- "cakephp/cakephp-codesniffer": "^2.0"
+ "phpunit/phpunit": "^5|^6",
+ "cakephp/cakephp": "~3.4",
+ "cakephp/cakephp-codesniffer": "~3.0"
 },
 "autoload": {
  "psr-4": {