ENH: Add additional environment to tox to run notebooks

Add an additional environment to `tox` to run notebooks.

Add a new table to `pyproject.toml` to host the `nbconvert` and
`nbclient` dependencies so that the notebooks can be run.

pyproject.toml

@@ -74,6 +74,11 @@ test = [
     "pytest-xdist >= 1.28"
 ]
 
+notebooks = [
+    "nbconvert",
+    "nbclient",
+]
+
 antsopt = [
     "ConfigSpace",
     "smac",

tox.ini

@@ -2,7 +2,7 @@
 requires =
   tox>=4
 envlist =
-  py312
+  py312, notebooks
 skip_missing_interpreters = true
 
 # Configuration that allows us to split tests across GitHub runners effectively
@@ -38,6 +38,33 @@ commands =
   pytest --doctest-modules --cov eddymotion -n auto --cov-report xml \
   --junitxml=test-results.xml -v src test {posargs}
 
+[testenv:notebooks]
+description = Run notebooks
+labels = notebooks
+pass_env =
+  # getpass.getuser() sources for Windows:
+  LOGNAME
+  USER
+  LNAME
+  USERNAME
+  # Pass user color preferences through
+  PY_COLORS
+  FORCE_COLOR
+  NO_COLOR
+  CLICOLOR
+  CLICOLOR_FORCE
+  CURBRANCH
+  GITHUB_ACTIONS
+  TEST_DATA_HOME
+  TEST_OUTPUT_DIR
+  TEST_WORK_DIR
+  PYTHONHASHSEED
+  ITK_GLOBAL_DEFAULT_NUMBER_OF_THREADS
+  PATH
+extras = notebooks
+commands =
+  python -m nbconvert --to notebook --ExecutePreprocessor.kernel_name=python3 --execute docs/notebooks/*
+
 [testenv:docs]
 description = Build documentation site
 labels = docs