Update jupyter classifiers

Author: timkpaine

jupyter/pyproject.toml.jinja

@@ -22,6 +22,9 @@ classifiers = [
     "Development Status :: 3 - Alpha",
     "Framework :: Jupyter",
     "Framework :: Jupyter :: JupyterLab",
+    "Framework :: Jupyter :: JupyterLab :: 4",
+    "Framework :: Jupyter :: JupyterLab :: Extensions",
+    "Framework :: Jupyter :: JupyterLab :: Extensions :: Prebuilt",
     "Programming Language :: Python",
     "Programming Language :: Python :: Implementation :: CPython",
     "Programming Language :: Python :: Implementation :: PyPy",