update badges

Author: jacobwilliams

README.md

@@ -7,9 +7,10 @@
 
 ## Status
 
-[![GitHub release](https://img.shields.io/github/release/jacobwilliams/NumDiff.svg?style=plastic)](https://github.com/jacobwilliams/NumDiff/releases/latest)
-![CI Status](https://github.com/jacobwilliams/NumDiff/actions/workflows/CI.yml/badge.svg)
-[![codecov](https://codecov.io/gh/jacobwilliams/NumDiff/branch/master/graph/badge.svg?token=43HK33CSMY)](https://codecov.io/gh/jacobwilliams/NumDiff)
+[![GitHub release](https://img.shields.io/github/release/jacobwilliams/NumDiff.svg)](https://github.com/jacobwilliams/NumDiff/releases/latest)
+[![Build Status](https://github.com/jacobwilliams/NumDiff/actions/workflows/CI.yml/badge.svg)](https://github.com/jacobwilliams/NumDiff/actions)
+[![codecov](https://codecov.io/gh/jacobwilliams/NumDiff/branch/master/graph/badge.svg)](https://codecov.io/gh/jacobwilliams/NumDiff)
+[![last-commit](https://img.shields.io/github/last-commit/jacobwilliams/NumDiff)](https://github.com/jacobwilliams/NumDiff/commits/master)
 
 This is currently a work in progress. The goal is a comprehensive library that contains a full suite of computationally efficient implementations of algorithms for sparsity determination and numerical differentiation. This code is hosted on GitHub at: https://github.com/jacobwilliams/NumDiff