ruff git dependencies need to be manually downloaded.

Fails to build with

   Compiling url v2.5.4
error[E0554]: `#![feature]` may not be used on the stable release channel
  --> /scratch/wip/py-pyrefly/work/vendor/static_interner-0.1.1/src/lib.rs:15:1
   |
15 | #![feature(offset_of)]
   | ^^^^^^^^^^^^^^^^^^^^^^

For more information about this error, try `rustc --explain E0554`.
error: could not compile `static_interner` (lib) due to 1 previous error