xtask build broken due to a subdependency

[nicholasbishop]

error: failed to select a version for the requirement `funty = "~1.2"`
candidate versions found which didn't match: 2.0.0, 1.1.0, 1.0.1, ...
location searched: crates.io index
required by package `bitvec v0.22.0`
    ... which satisfies dependency `bitvec = "^0.22"` of package `mbrman v0.5.0`
    ... which satisfies dependency `mbrman = "^0.5.0"` of package `xtask v0.0.0 (/home/nicholasbishop/src/uefi-rs/xtask)`

See ferrilab/funty#7 and rust-disk-partition-management/mbrman#24