automation: refresh requirements
I'm hitting errors installing the old version of cffi due to an
apparent issue where older versions of cffi aren't compatible with
the modern Clang I'm using. So let's upgrade packages to unbreak
things and to keep things modern.
Differential Revision: https://phab.mercurial-scm.org/D12629
$ rm -rf a
$ hg init a
$ cd a
$ echo a > a
$ hg ci -Am0
adding a
$ hg tag t1 # 1
$ hg tag --remove t1 # 2
$ hg co 1
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg tag -f -r0 t1
$ hg tags
tip 3:a49829c4fc11
t1 0:f7b1eb17ad24
$ cd ..