Change from debian:stable to debian:bullseye

[jgmize]

This fixes errors like the following when trying to build:

7.362 E: Unable to locate package libgdal28
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Dockerfile:21
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  20 |
  21 | >>> RUN apt-get update && apt-get install -y --no-install-recommends \
  22 | >>>     libgomp1 libgdal28 && apt-get clean
  23 |
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ERROR: failed to solve: process "/bin/sh -c apt-get update && apt-get install -y --no-install-recommends     libgomp1 libgdal28 && apt-get clean" did not complete successfully: exit code: 100