chore: remove Travis CI, switch to GitHub Actions

- Remove .travis.yml (deprecated)
- Replace Travis badge with GitHub Actions badge
- Remove duplicate Coveralls badge
- CI now runs via GitHub Actions workflow

Author: kolkov

.travis.yml

@@ -4,11 +4,10 @@
 
 # AngularEditor
 [![npm version](https://badge.fury.io/js/%40kolkov%2Fangular-editor.svg)](https://badge.fury.io/js/%40kolkov%2Fangular-editor)
+[![CI](https://github.com/kolkov/angular-editor/actions/workflows/publish.yml/badge.svg)](https://github.com/kolkov/angular-editor/actions/workflows/publish.yml)
 [![demo](https://img.shields.io/badge/demo-StackBlitz-blueviolet.svg)](https://stackblitz.com/edit/angular-editor-wysiwyg)
-[![Build Status](https://travis-ci.com/kolkov/angular-editor.svg?branch=main)](https://travis-ci.com/kolkov/angular-editor)
 [![npm](https://img.shields.io/npm/dm/@kolkov/angular-editor.svg)](https://www.npmjs.com/package/@kolkov/angular-editor)
 [![](https://data.jsdelivr.com/v1/package/npm/@kolkov/angular-editor/badge?style=rounded)](https://www.jsdelivr.com/package/npm/@kolkov/angular-editor)
-[![Coverage Status](https://coveralls.io/repos/github/kolkov/angular-editor/badge.svg?branch=main)](https://coveralls.io/github/kolkov/angular-editor?branch=main)
 [![codecov](https://codecov.io/gh/kolkov/angular-editor/branch/main/graph/badge.svg)](https://codecov.io/gh/kolkov/angular-editor)
 [![Donate](https://img.shields.io/badge/Donate-PayPal-green.svg)](https://paypal.me/AndreyKolkov)