Bump onnx, pillow, protobuf to resolve Dependabot alerts

Resolves all 13 open Dependabot advisories (8 high, 5 moderate):

- onnx 1.18.0 -> 1.21.0  (6: GHSA-3r9x-f23j-gc73, GHSA-538c-55jv-c5g9,
  GHSA-hqmj-h5c6-369m, GHSA-q56x-g2fj-4rj6, GHSA-cmw6-hcpp-c6jp,
  GHSA-p433-9wv8-28xj)
- pillow 12.1.1 -> 12.2.0  (5: GHSA-pwv6-vv43-88gr, GHSA-whj4-6x5x-4v2j,
  GHSA-5xmw-vc9v-4wf2, GHSA-r73j-pqj5-w3x7, GHSA-wjx4-4jcj-g98j)
- protobuf 4.25.1 -> 5.29.6  (2: GHSA-8qvm-5x2c-j2w7, GHSA-7gcm-g887-7qv7;
  the recursion-depth fix has no 4.x release, so 5.x is required)

protobuf 5.x caps tensorflow at 2.20.0 (2.21 needs protobuf>=6.31.1), which
keeps numpy at 1.26.x, preserving the existing numpy<2 pin. Verified with a
pip dry-run resolve and re-scanned the resulting set against OSV (all clean).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

requirements.txt

@@ -2,16 +2,16 @@ numpy>=1.23.5,<2
 typing-extensions>=4.8.0
 opencv-python==4.10.0.84
 cv2_enumerate_cameras==1.1.15
-onnx==1.18.0
+onnx==1.21.0
 insightface==0.7.3
 psutil==5.9.8
 PySide6>=6.7,<7
-pillow==12.1.1
+pillow==12.2.0
 tqdm>=4.65.0
 onnxruntime-silicon==1.16.3; sys_platform == 'darwin' and platform_machine == 'arm64'
 onnxruntime-gpu==1.23.2; sys_platform != 'darwin'
 tensorflow>=2.15.0; sys_platform != 'darwin'
 tensorflow>=2.15.0; sys_platform == 'darwin' and python_version < '3.13'
 opennsfw2==0.10.2
-protobuf==4.25.1
+protobuf==5.29.6
 pygrabber; sys_platform == 'win32'