Bump numpy from 1.26.3 to 1.26.4 in /requirements (AtsushiSakai#977)

Bumps [numpy](https://github.com/numpy/numpy) from 1.26.3 to 1.26.4.
- [Release notes](https://github.com/numpy/numpy/releases)
- [Changelog](https://github.com/numpy/numpy/blob/main/doc/RELEASE_WALKTHROUGH.rst)
- [Commits](numpy/numpy@v1.26.3...v1.26.4)

---
updated-dependencies:
- dependency-name: numpy
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

requirements/requirements.txt

@@ -1,4 +1,4 @@
-numpy == 1.26.3
+numpy == 1.26.4
 scipy == 1.12.0
 matplotlib == 3.8.2
 cvxpy == 1.4.2