use edge repository for php dependencies

Dockerfile

@@ -10,7 +10,12 @@ LABEL build_version="Linuxserver.io version:- ${VERSION} Build-date:- ${BUILD_DA
 RUN \
  apk add --no-cache \
 	imagemagick \
-	ffmpeg \
+	ffmpeg && \
+ apk add --no-cache \
+	--repository http://nl.alpinelinux.org/alpine/edge/main \
+	libwebp && \
+ apk add --no-cache \
+	--repository http://nl.alpinelinux.org/alpine/edge/community \
 	php7-gd && \
 
 # configure php