bump cuda-bindings floors to 12.9.3 (CUDA 12) and 13.0.2 (CUDA 13)

[jameslamb]

NVIDIA/cudf#21928 bumped cudf's cuda-bindings floors, and as a result CI is breaking on main here for "oldest-deps" jobs

error    libmamba Could not solve for environment specs
    The following packages are incompatible
    ├─ cuda-bindings ==12.9.2 * is requested and can be installed;
    └─ cugraph =26.12,>=0.0.0a0 * is not installable because there are no viable options
       ├─ cugraph 26.12.00a15 would require
       │  └─ pylibcudf =26.12 * but there are no viable options
       │     ├─ pylibcudf [26.12.00a0|26.12.00a10|...|26.12.00a9] would require
       │     │  └─ cuda-bindings >=12.9.3,<13.0 *, which conflicts with any installable versions previously reported;
       │     └─ pylibcudf [26.12.00a0|26.12.00a10|...|26.12.00a9] would require
       │        └─ cuda-bindings >=13.0.2,<14.0 *, which conflicts with any installable versions previously reported;
       └─ cugraph [26.12.00a0|26.12.00a11|26.12.00a4|26.12.00a9] conflicts with any installable versions previously reported.
critical libmamba Could not solve for environment specs

(build link)

This fixes that by bumping cugraph's floors to match.

[bdice]

/merge