This fixes a bug on Windows where `Command::new` would also run
executables from the current working directory, possibly resulting in
accidental runs of programs called `less`.
Less 581.2 is here, and it has a ".2" in the version string, which can't
be parsed as a usize.
Update the check to find a non-digit character rather than a space. This
ignores the minor version, but parses the major version correctly.
