Fixing permissions of ffmpeg and ffprobe

Since we didn't specify UID and GID in copy command before, they were run as root causing permissions conflicts
The ffmpeg stage doesn't need the env variables henceforth

Dockerfile

@@ -1,13 +1,12 @@
 FROM ubuntu:22.04 AS ffmpeg
 
-ENV UID=1000 \
-  GID=1000 \
-  USER=youtube \
-  DEBIAN_FRONTEND=noninteractive
+ENV DEBIAN_FRONTEND=noninteractive
 
 COPY docker-build.sh .
 RUN sh ./docker-build.sh
 
+#--------------# Stage 2
+
 FROM ubuntu:22.04 as frontend
 
 ENV DEBIAN_FRONTEND=noninteractive
@@ -31,7 +30,7 @@ COPY [ "angular.json", "tsconfig.json", "/build/" ]
 COPY [ "src/", "/build/src/" ]
 RUN npm run build
 
-#--------------#
+#--------------# Final Stage
 
 FROM ubuntu:22.04
 
@@ -56,8 +55,8 @@ RUN apt-get update && apt-get -y install \
   rm -rf /var/lib/apt
 
 WORKDIR /app
-COPY --from=ffmpeg /usr/local/bin/ffmpeg /usr/local/bin/ffmpeg
-COPY --from=ffmpeg /usr/local/bin/ffprobe /usr/local/bin/ffprobe 
+COPY --chown=$UID:$GID --from=ffmpeg [ "/usr/local/bin/ffmpeg", "/usr/local/bin/ffmpeg" ]
+COPY --chown=$UID:$GID --from=ffmpeg [ "/usr/local/bin/ffprobe", "/usr/local/bin/ffprobe" ]
 COPY --chown=$UID:$GID [ "backend/package.json", "backend/package-lock.json", "/app/" ]
 ENV PM2_HOME=/app/pm2
 RUN npm config set strict-ssl false && \