Improve handling of ConnectionError

See merge request !122

Unfortunately, the mypy check has been rotting for years now. Let's not
pretend like this check is maintained and remove the associated code.

This entire commit is just the result of running `black` formatter on
the python files - no manual changes were made.

In a ConnectionError happens, try and capture the information for which
resolver it occurred. While it may be just a regular one-off network
blip, it may also indicate a failure mode in one of the target
resolvers. That is especially true if the same connection error happens
repeatedly for a single resolver.

Prior to this change, the information about the resolver was lacking.
This made it hard to assess whether the connection errors were caused by
some network issue, or if it's likely that one of the target resolver is
at fault.

respdiff/repro: convert qids to list when sampling

See merge request !121

Fixes compatibility with Python >=3.11, where `random.sample()` no
longer accepts non-sequence `population`.

See <https://docs.python.org/3.11/library/random.html#random.sample>.

Only add it to the build env.  That way each kresd build can decide
if it wants to use jemalloc or not.  (so older version keep building)

Ubuntu 21.10 (Impish) has reached end-of-life and the image could no
longer be built.

contrib: add distrotest for rocky8

See merge request !116

contrib/docker: utility scripts for image updates

See merge request !115

respdiff: downgrade bind to previous working version

See merge request !114

contrib: update resolvers

See merge request !113

orchestrator: fix progress report

See merge request !112

For some reason, the code reading answers was using imap() function to
read them _in order_ they were sent. This could cause answer buildup
in an internal multiprocessing queue, and eventually the program logged
multiple 'Received xxx answers' lines at once, which made the status
reporting useless.

It was like that since d422292d, and
this commit claims it reduced storage requirements by factor 25.
The problem is that the commit did three changes at once:
- it moved txn.put() into central place in the main thread
- it coalesced all writes into one huge transactoin
- it changed imap_unordered() to imap() call

In my tests today, centralized txn.put() in the main thread in
combination with one huge transaction and imap_unordered() increases
storage size by 5 %, and that does not seem worth incorrect status
reporting.

Tested with LMDB version 0.9.29.

contrib/job_manager: add ubuntu2110, fedora35, delete older

See merge request !111

ci: update to knot 3.1 and debian 11

See merge request !110

use respdiff-rs version of msgdiff

See merge request !109

contrib/job_manager: add distrotests for debian11

See merge request !108

contib: update fedora, ubuntu releases

See merge request !107

diffsum: display msgid for queries

See merge request !106