Docker image is out of date (grab-site 2.1.18, Python 3.7.6)

[exurd]

The image was last updated 5 years ago and uses a really old version of grab-site.

# grab-site --version
2.1.18
# python -V
Python 3.7.6

Unfortunately, the image currently cannot be rebuilt due to google-re2 deprecating Python 3.8 (google/re2#559, ArchiveTeam/grab-site#245).

[exurd]

ArchiveTeam/grab-site#248 will allow the image to be rebuilt; it just needs to be merged into the master branch.