Update package.json

Sharp 0.32.0 wasn't building

Author: Ckoelewyn

package.json

@@ -56,7 +56,7 @@
     "reproject": "~1.2.2",
     "request": "~2.88.0",
     "request-promise-native": "~1.0.7",
-    "sharp": "~0.32.0",
+    "sharp": "~0.23.0",
     "stream": "~0.0.2",
     "stream-transform": "~2.0.1",
     "swagger-tools": "~0.10.4",