build: Use notebook over jupyter (#2507)

* jupyter is a metapackage that is never updated, so defining the
  notebook dependency provides better control on the actual tools
  required.

pyproject.toml

@@ -109,7 +109,7 @@ test = [
     "pydocstyle",
     "papermill>=2.5.0",
     "scrapbook>=0.5.0",
-    "jupyter",
+    "notebook>=6.5.7",
     "graphviz",
     "pytest-socket>=0.2.0",  # c.f. PR #1917
 ]