One or more of the transitive dependencies needs Rust 1.88 or newer, so
this becomes our minimum version. It may be possible to build with an
older Rust by manually picking dependency versions but I'm not going to
do that.
Ideally, `-Zminimal-versions` would pick out those versions, but lots of
crates don't correctly specify minimum depdendency versions. As a
result, our transitive dependencies resolve to
matching-but-non-functional versions.
Semver checks only make sense for things that have a public interface.
While an application technically does, these semver checks are for the
Rust API not the GUI shape or something. It's for checking that a
library upholds it's semver promise.
This is not a library, so these checks don't make sense.
