Version 2.7.3 is the last one that is licensed under MPL-2.0. Upstream has
switched to some license with restriction of use for "Research purposes" since
version 2.7.4.

See the discussion at
    https://github.com/epi2me-labs/pychopper/issues/27
and possibly follow-up documented on
    https://wiki.debian.org/DebianMed/SoftwareLiberation

If we want to keep pychopper in main, then we are stuck with version 2.7.3 for
the moment.

 -- Pierre Gruet <pgt@debian.org>  Sun, 18 Jun 2023 14:27:19 +0200
