Bump pandas from 1.1.3 to 1.1.4 (#431)

Bumps [pandas](https://github.com/pandas-dev/pandas) from 1.1.3 to 1.1.4.
- [Release notes](https://github.com/pandas-dev/pandas/releases)
- [Changelog](https://github.com/pandas-dev/pandas/blob/master/RELEASE.md)
- [Commits](https://github.com/pandas-dev/pandas/compare/v1.1.3...v1.1.4)

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

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

requirements.txt

@@ -1,5 +1,5 @@
 numpy == 1.19.4
 scipy == 1.5.3
-pandas == 1.1.3
+pandas == 1.1.4
 matplotlib == 3.3.2
 cvxpy == 1.1.7