STM: Update build status icon to use Github Actions
ZMap: The Internet Scanner
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-[![Build Status](https://travis-ci.org/zmap/zmap.svg?branch=travis-configuration)](https://travis-ci.org/zmap/zmap)
+![Build Status](https://github.com/zmap/zmap/actions/workflows/cmake.yml/badge.svg)
ZMap is a fast single packet network scanner designed for Internet-wide network
surveys. On a typical desktop computer with a gigabit Ethernet connection, ZMap
