feat: add non root user (#7)

Dockerfile

@@ -1,9 +1,20 @@
 # Use Alpine base image with edge repository
 FROM --platform=${BUILDPLATFORM} alpine:edge
 
+ARG PGID=1000
+ARG PUID=1000
+ENV PGID=${PGID}
+ENV PUID=${PUID}
+ENV USER=app
+ENV TZ="UTC"
+
 # hadolint ignore=DL3018
-RUN apk update && \
+RUN addgroup -g ${PGID} ${USER} && \
+    adduser -D -u ${PUID} -G ${USER} ${USER} && \
+    apk update && \
     apk add --no-cache curl bash ffmpeg yt-dlp && \
     yt-dlp --version
 
+USER app
+
 ENTRYPOINT ["yt-dlp"]