Bump pandas from 1.3.5 to 1.4.0

Bumps [pandas](https://github.com/pandas-dev/pandas) from 1.3.5 to 1.4.0.
- [Release notes](https://github.com/pandas-dev/pandas/releases)
- [Changelog](https://github.com/pandas-dev/pandas/blob/main/RELEASE.md)
- [Commits](https://github.com/pandas-dev/pandas/compare/v1.3.5...v1.4.0)

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

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

requirements.txt

@@ -1,6 +1,6 @@
 numpy==1.21.5; python_version <= '3.7'
 numpy==1.22.1; python_version > '3.7'
-pandas==1.3.5
+pandas==1.4.0
 pandas-ta==0.3.14b
 
 ccxt==1.68.20