fix(package): update sharp to version 0.25.2

Closes #141

Author: greenkeeper[bot]

package.json

@@ -46,7 +46,7 @@
     "plugin-error": "^1.0.1",
     "plur": "^3.1.1",
     "rename": "^1.0.4",
-    "sharp": "^0.23.1",
+    "sharp": "^0.25.2",
     "through2": "^3.0.1",
     "vinyl": "^2.2.0"
   },