Bump Mercurial to 5.5 and extensions
Given that the tests for py-heptapod work for Mercurial 5.5, using it in Heptapod (instead of the current 5.4.2) should be straightforward, implying only to bump Evolve and hg-git as well
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information