(maint) Update inifile dependency

This commit updates the module's metadata.json to permit the most
recent version (6.0.0)  of the inifile module as a dependency.

Author: mhashizume

metadata.json

@@ -14,7 +14,7 @@
     },
     {
       "name": "puppetlabs-inifile",
-      "version_requirement": ">= 2.4.0 < 6.0.0"
+      "version_requirement": ">= 2.4.0 < 7.0.0"
     },
     {
       "name": "puppetlabs-apt",