FIX: Include leading dots in extensions

Author: effigies

templateflow/conf/config.json

@@ -68,7 +68,7 @@
         },
         {
             "name": "extension",
-            "pattern": "[._]*[a-zA-Z0-9]*?\\.([^/\\\\]+)$"
+            "pattern": "[._]*[a-zA-Z0-9]*?(\\.[^/\\\\]+)$"
         }
     ],
     "default_path_patterns": [