Install numpy before GDAL

[GerbenJdeBoer]

Great docker file, it solved my GDAL installation issues. Suggestion: add
RUN pip3 install numpy
before
RUN pip3 install GDAL==3.0.4
so ReadAsAssary works in this example

driver = gdal.GetDriverByName('GTiff')
dataset = gdal.Open(file_name)
band = dataset.GetRasterBand(1)
band.ReadAsArray(i1, j1, new_cols, new_rows)

thanx to https://gis.stackexchange.com/questions/153199/import-error-no-module-named-gdal-array