Bump scipy from 1.8.0 to 1.8.1 in /requirements (AtsushiSakai#686)

Bumps [scipy](https://github.com/scipy/scipy) from 1.8.0 to 1.8.1.
- [Release notes](https://github.com/scipy/scipy/releases)
- [Commits](scipy/scipy@v1.8.0...v1.8.1)

---
updated-dependencies:
- dependency-name: scipy
  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

@@ -1,5 +1,5 @@
 numpy == 1.22.4
-scipy == 1.8.0
+scipy == 1.8.1
 pandas == 1.4.2
 matplotlib == 3.5.2
 cvxpy == 1.2.1