Bump paddlepaddle from 2.5.0 to 2.6.1 in /tests

Bumps [paddlepaddle](https://github.com/paddlepaddle/paddle) from 2.5.0 to 2.6.1.
- [Release notes](https://github.com/paddlepaddle/paddle/releases)
- [Changelog](https://github.com/PaddlePaddle/Paddle/blob/develop/RELEASE.md)
- [Commits](PaddlePaddle/Paddle@v2.5.0...v2.6.1)

---
updated-dependencies:
- dependency-name: paddlepaddle
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

tests/constraints.txt

@@ -13,7 +13,7 @@ fastjsonschema~=2.17.1
 test-generator==0.1.2
 requests>=2.25.1
 opencv-python>=4.5
-paddlepaddle==2.5.0
+paddlepaddle==2.6.1
 py>=1.9.0
 pytest>=5.0,<7.5
 pytest-dependency==0.5.1