Bump numpy from 1.21.3 to 1.21.4 (AtsushiSakai#558)

Bumps [numpy](https://github.com/numpy/numpy) from 1.21.3 to 1.21.4.
- [Release notes](https://github.com/numpy/numpy/releases)
- [Changelog](https://github.com/numpy/numpy/blob/main/doc/HOWTO_RELEASE.rst.txt)
- [Commits](numpy/numpy@v1.21.3...v1.21.4)

---
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.txt

@@ -1,4 +1,4 @@
-numpy == 1.21.3
+numpy == 1.21.4
 scipy == 1.7.1
 pandas == 1.3.4
 matplotlib == 3.4.3