Update torchvision requirement from ~=0.23.0 to ~=0.26.0+cpu in /tests

Updates the requirements on torchvision to permit the latest version.

---
updated-dependencies:
- dependency-name: torchvision
  dependency-version: 0.26.0+cpu
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

tests/constraints.txt

@@ -24,4 +24,4 @@ kornia==0.8.2
 
 --extra-index-url https://download.pytorch.org/whl/cpu
 torch~=2.8.0
-torchvision~=0.23.0
+torchvision~=0.26.0+cpu