Switch from Travis-CI to GitHub Actions

Author: adamretter

.github/workflows/ci.yml

@@ -0,0 +1,20 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+
+jobs:
+  build:
+    name: Build
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+    runs-on: ${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v2
+      - name: Make
+        run: make

.travis.yml

@@ -1,13 +1,12 @@
 # UTF8 Validator (C edition)
 
-This is a more basic but faster version of [UTF8 Validator](https://github.com/digital-preservation/utf8-validator). The C edition, uses the [fastvalidate-utf-8](https://github.com/lemire/fastvalidate-utf-8) library from [Daniel Lemire](https://github.com/lemire). The C edition only returns a pass or fail result. It does not provide information about the position at which validation fails or allow to continue validating further after the first error.
+This is a more basic but much faster version of [UTF8 Validator](https://github.com/digital-preservation/utf8-validator). The C edition, uses the [fastvalidate-utf-8](https://github.com/lemire/fastvalidate-utf-8) library from [Daniel Lemire](https://github.com/lemire). The C edition only returns a pass or fail result. It does not provide information about the position at which validation fails or allow to continue validating further after the first error.
 
 A UTF-8 Validation Tool which may be used as a command line tool, if you are looking for a C library to use with your own program see [fastvalidate-utf-8](https://github.com/lemire/fastvalidate-utf-8).
 
 Released under the [Apache 2.0 Licence](https://opensource.org/licenses/Apache-2.0).
 
-[![Build Status](https://travis-ci.org/adametter/utf8-validator-c.png?branch=master)](https://travis-ci.org/adamretter/utf8-validator-c)
-
+[![CI](https://github.com/adamretter/utf8-validator-c/workflows/CI/badge.svg)](https://github.com/adamretter/utf8-validator-c/actions?query=workflow%3ACI)
 
 ## Use from the Command Line
 You can [build from the source code](#building-from-source-code). You can then run `utf8validate` (Linux/Mac/Unix).