Add pyusb as explicit dependency in gs-usb optional group

The gs_usb interface directly imports `usb` (pyusb) for USB device
discovery, so pyusb must be an explicit dependency rather than relying
on it being a transitive dependency of the gs-usb package.

Co-authored-by: BenGardiner <243321+BenGardiner@users.noreply.github.com>

Author: Copilot

pyproject.toml

@@ -64,7 +64,7 @@ neovi = ["filelock", "python-ics>=2.12"]
 canalystii = ["canalystii>=0.1.0"]
 cantact = ["cantact>=0.0.7"]
 cvector = ["python-can-cvector"]
-gs-usb = ["gs-usb>=0.2.1"]
+gs-usb = ["gs-usb>=0.2.1", "pyusb>=1.0.2"]
 nixnet = ["nixnet>=0.3.2"]
 pcan = ["uptime~=3.0.1"]
 remote = ["python-can-remote"]