Bump ipython from 7.30.1 to 7.31.1 in /docs (AtsushiSakai#628)

Bumps [ipython](https://github.com/ipython/ipython) from 7.30.1 to 7.31.1.
- [Release notes](https://github.com/ipython/ipython/releases)
- [Commits](ipython/ipython@7.30.1...7.31.1)

---
updated-dependencies:
- dependency-name: ipython
  dependency-type: direct:production
...

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Author: dependabot[bot]

docs/doc_requirements.txt

@@ -1,3 +1,3 @@
 sphinx == 4.3.2 # For sphinx documentation
 sphinx_rtd_theme == 1.0.0
-IPython == 7.30.1 # For sphinx documentation
+IPython == 7.31.1 # For sphinx documentation