Increase minimum puppetlabs-stdlib version requirement

ensure_resources which is used in the 'ceph::osds' and 'ceph::conf'
classes only came in at 4.12.0 so increase version to that.

Change-Id: I2141523b9bf295d3f5297b714faa2897b2d2d66f

metadata.json

@@ -65,11 +65,11 @@
         },
         {
             "name": "puppetlabs/stdlib",
-            "version_requirement": ">=4.10.0 <5.0.0"
+            "version_requirement": ">=4.12.0 <5.0.0"
         },
         {
             "name": "duritong/sysctl",
             "version_requirement": ">=0.0.1 <1.0.0"
         }
     ]
-}
+}