Dependencies in Debian Bullseye

I have opened a can of worms, by attempting to apt-get -s install lalsuite-all. While I'm aware of the changes being made wrt/ python2->3 and so on, I'd like to list my findings here.

1. lscsoft-auth needs python-krbv which appears abandoned after Buster - any replacement?
2. lscsoft-external depends on swig3.0 and swig3.0-doc --> add alternative | swig4.0 / | swig4.0-doc (or, even better, use swig (>= 3) / swig-doc (>= 3))
3. currently there's no condor, pegasus (because of Python3 only)
4. lscsoft-external-python asks for pep8 which even in Stretch is a transitional package, apparently for pycodestyle (which is the only dependency in Stretch), but there's also python*-pep8 - what would be the correct replacement?
5. currently there's no lalapps, gstlal* (because of Python3 only)
6. lscsoft-lalsuite-dev has a dependency on swig3.0 --> add alternative | swig4.0 (or use swig (>= 3))
7. currently there's no ROOT for Debian >> Stretch/Buster (and no chance to rebuild ROOT 5), so no gds*
8. ldas-tools-framecpp is broken, https://git.ligo.org/ldastools/LDAS_Tools/-/issues/99 and https://git.ligo.org/ldastools/LDAS_Tools/-/issues/97
9. finesse (version 2 at least) has a hard requirement on x86 architectures - affecting lscsoft-internal that also depends on python*-pykat.

So in short, we're affected mostly by the lack of

• support for Python3 both in external condor and pegasus, and internal lalapps and friends
• ROOT (it's on my list, but too far down, I'm afraid)
• response to build errors

@adam-mercer Can you make the swig additions/modifications without having me to clone the whole repo, submit a MR, see the MR fail while other changes are being made, and have to go full circle for a three-line change?