Replace Travis CI with GitHub Actions

Travis is pretty much dead

in the process, added ppc64le as suggested by @kishorkunal-raj

.github/workflows/tests.yaml

@@ -0,0 +1,22 @@
+name: tests
+on: push
+jobs:
+    build:
+        runs-on: ubuntu-latest
+        strategy:
+            matrix:
+                architecture:
+                - x64
+                - ppc64le
+                node-version:
+                - 14.x
+                - 12.x
+                - 10.x
+        name: ${{ matrix.node-version }} on ${{ matrix.architecture }}
+        steps:
+        - uses: actions/checkout@v2
+        - uses: actions/setup-node@v2
+          with:
+              architecture: ${{ matrix.architecture }}
+              node-version: ${{ matrix.node-version }}
+        - run: npm install-test

Readme.md

@@ -1,5 +1,5 @@
 # [Base62.js](http://libraries.io/npm/base62)
-[![build status](https://secure.travis-ci.org/base62/base62.js.svg)](http://travis-ci.org/base62/base62.js)
+[![build status](https://github.com/base64/base64.js/workflows/tests/badge.svg)](https://github.com/base64/base64.js/actions)
 [![npm version](https://badge.fury.io/js/base62.svg)](http://badge.fury.io/js/base62)
 [![devDependency Status](https://david-dm.org/base62/base62.js/dev-status.svg?theme=shields.io)](https://david-dm.org/base62/base62.js#info=devDependencies)
 [![Gitter chat](http://img.shields.io/badge/gitter-base62/base62.js-brightgreen.svg)](https://gitter.im/base62/base62.js)