fix error in badge URL

Author: petercorke

README.md

@@ -5,7 +5,7 @@
 
 [![PyPI version](https://badge.fury.io/py/spatialmath-python.svg)](https://badge.fury.io/py/spatialmath-python)
 [![Anaconda version](https://anaconda.org/conda-forge/spatialmath-python/badges/version.svg)](https://anaconda.org/conda-forge/spatialmath-python)
-![Python Version](https://img.shields.io/pypi/pyversions/roboticstoolbox-python.svg)
+![Python Version](https://img.shields.io/pypi/pyversions/spatialmath-python.svg)
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
 
 [![Build Status](https://github.com/petercorke/spatialmath-python/workflows/build/badge.svg?branch=master)](https://github.com/petercorke/spatialmath-python/actions?query=workflow%3Abuild)