Update ipython requirement from ~=7.15.0 to ~=7.16.1 (#606)

Updates the requirements on [ipython](https://github.com/ipython/ipython) to permit the latest version.
- [Release notes](https://github.com/ipython/ipython/releases)
- [Commits](ipython/ipython@7.15.0...7.16.1)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Author: dependabot-preview[bot]

requirements-dev.txt

@@ -4,7 +4,7 @@ pyflakes ~=2.2.0
 pytest ~=5.4.3
 vcrpy ~=4.0.2
 doctr ~=1.8.0
-ipython ~=7.15.0
+ipython ~=7.16.1
 matplotlib ~=3.2.2
 numpydoc ~=1.0.0
 requests-mock ~=1.8.0