add axiosist to ECOSYSTEM.md (#963)

ECOSYSTEM.md

@@ -13,3 +13,4 @@ This is a list of axios related libraries and resources. If you have a suggestio
 * [axios-debug-log](https://github.com/Gerhut/axios-debug-log) - Axios interceptor of logging requests & responses by debug.
 * [axios-method-override](https://github.com/jacobbuck/axios-method-override) - Axios http request method override plugin
 * [mocha-axios](https://github.com/jdrydn/mocha-axios) - Streamlined integration testing with Mocha & Axios
+* [axiosist](https://github.com/Gerhut/axiosist) - Axios based supertest: convert node.js request handler to axios adapter, used for node.js server unit test.