Added test badge

Author: scriptcoded

README.md

@@ -1,6 +1,7 @@
 # simple-pdf
 
 [![npm](https://img.shields.io/npm/v/simple-pdf)](https://www.npmjs.com/package/simple-pdf)
+[![Tests](https://github.com/scriptcoded/simple-pdf/workflows/Tests/badge.svg)](https://github.com/scriptcoded/simple-pdf/actions?query=workflow%3ATests)
 [![david-dm](https://david-dm.org/scriptcoded/simple-pdf.svg)](https://david-dm.org/scriptcoded/simple-pdf)
 
 `simple-pdf` aims to be a simple drop-in module for extracting text and images