updated version constraint in extension template

avoid unbound constraints

yiisoft/yii2#12154

composer.json

@@ -15,16 +15,17 @@
     "minimum-stability": "dev",
     "require": {
         "php": ">=5.4.0",
-        "yiisoft/yii2": ">=2.0.5",
-        "yiisoft/yii2-bootstrap": "*",
-        "yiisoft/yii2-swiftmailer": "*"
+        "yiisoft/yii2": "~2.0.5",
+        "yiisoft/yii2-bootstrap": "~2.0.0",
+        "yiisoft/yii2-swiftmailer": "~2.0.0"
     },
     "require-dev": {
+        "yiisoft/yii2-debug": "~2.0.0",
+        "yiisoft/yii2-gii": "~2.0.0",
+        "yiisoft/yii2-faker": "~2.0.0",
+
         "codeception/base": "^2.2.3",
         "codeception/verify": "~0.3.1",
-        "yiisoft/yii2-debug": "*",
-        "yiisoft/yii2-gii": "*",
-        "yiisoft/yii2-faker": "*",
         "codeception/specify": "~0.4.3"
     },
     "config": {