message: Change python to python2
  As python in alpine 3.11 is version 2.x.x and python in alpine 3.13 have two python versions ```python3``` and ```python2```.
diff: #-----------------BUILDER-----------------
  #-----------------------------------------
  FROM node:14-alpine3.13 AS builder
  -ARG VERSION
  RUN apk add --update-cache --repository https://alpine.global.ssl.fastly.net/alpine/v3.13/community/ \
  - python2 build-base sqlite-dev sqlite-libs vips-dev fftw-dev gcc g++ make libc6-compat unzip
  + python2 build-base sqlite-dev sqlite-libs vips-dev fftw-dev gcc g++ make libc6-compat
  +COPY pigallery2-release /app
  WORKDIR /app
  -ADD https://github.com/bpatrik/pigallery2/releases/download/$VERSION/pigallery2-release.zip /app
  -RUN unzip pigallery2-release.zip -d /app
  RUN npm install --unsafe-perm
  RUN mkdir -p /app/data/config && \
  mkdir -p /app/data/db && \
  mkdir -p /app/data/images && \
  mkdir -p /app/data/tmp
  +
  #-----------------MAIN--------------------
  #-----------------------------------------
  FROM node:14-alpine3.13 AS main
  @@ -24,15 +23,16 @@ ENV NODE_ENV=production \
  default-Server-Media-tempFolder=/app/data/tmp \
  # flagging dockerized environemnt
  PI_DOCKER=true
  +
  EXPOSE 80
  RUN apk add --update-cache --repository https://alpine.global.ssl.fastly.net/alpine/v3.13/community/ \
  vips ffmpeg
  -COPY --from=builder --chown=node:node /app /app
  -USER node
  +COPY --from=builder /app /app
  VOLUME ["/app/data/config", "/app/data/db", "/app/data/images", "/app/data/tmp"]
  HEALTHCHECK --interval=40s --timeout=30s --retries=3 --start-period=60s \
  CMD wget --quiet --tries=1 --no-check-certificate --spider \
  http://localhost:80/heartbeat || exit 1
  +
  # after a extensive job (like video converting), pigallery calls gc, to clean up everthing as fast as possible
  # Exec form entrypoint is need otherwise (using shell form) ENV variables are not properly passed down to the app
  ENTRYPOINT ["node", "./src/backend/index", "--expose-gc", "--config-path=/app/data/config/config.json"]
  