build(deps): update ipython requirement (#548)

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@rel-0.8.4...8.16.0)

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

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Author: dependabot[bot]

docs/requirements.txt

@@ -1,2 +1,2 @@
 # this is only required by coconut kernel
-ipython<=8.15.0
+ipython<=8.16.0

pyproject.toml

@@ -92,7 +92,7 @@ testing = [
     # for issue with 8.1.0 see https://github.com/ipython/ipython/issues/13554
     # TODO ipython 8.5 subtly changes output of test regressions
     # see https://ipython.readthedocs.io/en/stable/whatsnew/version8.html#restore-line-numbers-for-input
-    "ipython!=8.1.0,<8.16",
+    "ipython!=8.1.0,<8.17",
     "ipywidgets>=8",
     "jupytext>=1.11.2,<1.16.0",
     "matplotlib>=3.5.3,<3.6",  # TODO mpl 3.6 subtly changes output of test regressions