crate importer throws

[jgart <jgart@dismail.de>]

```
 λ guix import crate the-way
;;; Failed to autoload string->semver-range in (semver ranges):
;;; no code for module (semver ranges)
Backtrace:
In ice-9/boot-9.scm:
  1752:10  9 (with-exception-handler _ _ #:unwind? _ # _)
In unknown file:
           8 (apply-smob/0 #<thunk 7f6f033b62e0>)
In ice-9/boot-9.scm:
    724:2  7 (call-with-prompt _ _ #<procedure default-prompt-handle…>)
In ice-9/eval.scm:
    619:8  6 (_ #(#(#<directory (guile-user) 7f6f033bbc80>)))
In guix/ui.scm:
   2263:7  5 (run-guix . _)
  2226:10  4 (run-guix-command _ . _)
In guix/scripts/import.scm:
    92:11  3 (guix-import . _)
In guix/scripts/import/crate.scm:
    95:24  2 (guix-import-crate . _)
In guix/import/crate.scm:
    287:9  1 (crate->guix-package "the-way" #:version _ # _ #:repo _)
   260:26  0 (find-crate-version #<<crate> name: "the-way" latest-v…> …)

guix/import/crate.scm:260:26: In procedure find-crate-version:
error: string->semver-range: unbound variable
```

WDYT