Upgrade libvips to 8.6.3

Author: bgv

Dockerfile

@@ -1,8 +1,8 @@
 FROM alpine:3.5
 
 # Environment Variables
-ARG LIBVIPS_VERSION_MAJOR_MINOR=8.5
-ARG LIBVIPS_VERSION_PATCH=9
+ARG LIBVIPS_VERSION_MAJOR_MINOR=8.6
+ARG LIBVIPS_VERSION_PATCH=3
 ARG MOZJPEG_VERSION="v3.2"
 
 # Install dependencies