setup: drop support for Python 3.5
We talked about this on the mailing list [1] and there seemed to be
agreement that Python 3.5 is effectively dead and no longer worth
supporting.
So this commit changes our minimum version requirement to 3.6.2.
[1] https://www.mercurial-scm.org/pipermail/mercurial-devel/2022-February/147885.html
Differential Revision: https://phab.mercurial-scm.org/D12315
$ hg init
$ echo 123 > a
$ hg add a
$ hg commit -m "first" a
$ mkdir sub
$ echo 321 > sub/b
$ hg add sub/b
$ hg commit -m "second" sub/b
$ cat sub/b
321
$ hg co 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ cat sub/b 2>/dev/null || echo "sub/b not present"
sub/b not present
$ test -d sub || echo "sub not present"
sub not present