Update Dockerfile for quicker build and slimmer image #355

Is your feature request related to a problem? Please describe.
Docker image builds take a long time, renders a quite big Docker Image (around 500MB uncompressed).
Mainly due to using Alpine base image without wheels.

Describe the solution you'd like
Quicker builds using APT packages, using Debian or Ubuntu (or python) slim base image. Or maybe even GDAL Base image.

Describe alternatives you've considered
Slimming Alpine Docker image but a long and error-prone process.

Additional context
Other Python geospatial projects like Stetl and pygeoapi use Debian/Ubuntu base images.