Update Dockerfile

Author: lintbe

Dockerfile

@@ -1,6 +1,6 @@
 FROM alpine:edge AS build
 
-RUN apk add --update --no-cache gcc g++ clang make cmake musl-dev unzip wget libpng pkgconf
+RUN apk add --update --no-cache gcc g++ clang make cmake musl-dev unzip wget libpng-dev pkgconf
 
 WORKDIR /usr/src