Fix py.path.local stat call in uboot fixture — use .size() not .stat().st_size

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: mangelajo

python/packages/jumpstarter-driver-uboot/jumpstarter_driver_uboot/driver_test.py

@@ -49,7 +49,7 @@ def uboot_image(tmpdir_factory):
             fd = rpm.extractfile("./usr/share/uboot/qemu_arm64/u-boot.bin")
             with bin_path.open("wb") as f:
                 f.write(fd.read())
-    print(f"Extracted u-boot.bin ({bin_path.stat().st_size} bytes)")
+    print(f"Extracted u-boot.bin ({bin_path.size()} bytes)")
 
     yield bin_path