update py version

Author: petercorke

symbolic/angvelxform_dot.ipynb

@@ -267,7 +267,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.8.5"
+   "version": "3.9.15"
   },
   "varInspector": {
    "cols": {