Move from Travic to GitHub actions and update readme (#17)

Author: ckipp01

.github/ci.yml

@@ -0,0 +1,19 @@
+name: Build/test
+on:
+  push:
+    branches:
+      - "**"
+jobs:
+  test:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: true
+      matrix:
+        os: [macos-latest, ubuntu-latest, windows-latest]
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-node@v2
+        with:
+          node-version: 14
+      - run: npm install
+      - run: npm test

.travis.yml

@@ -1,14 +1,14 @@
 tree-sitter-scala
 =================
 
-[![Build Status](https://travis-ci.org/tree-sitter/tree-sitter-scala.svg?branch=master)](https://travis-ci.org/tree-sitter/tree-sitter-scala)
+[![Test the grammar](https://github.com/tree-sitter/tree-sitter-scala/actions/workflows/ci.yml/badge.svg)](https://github.com/tree-sitter/tree-sitter-scala/actions/workflows/ci.yml)
 
 Scala grammar for [tree-sitter](https://github.com/tree-sitter/tree-sitter).
 
 References
 
-* [The Scala Language Specification](http://www.scala-lang.org/docu/files/ScalaReference.pdf)
-* [Scala Syntax Summary](https://www.scala-lang.org/files/archive/spec/2.11/13-syntax-summary.html)
+* [The Scala Language Specification](https://www.scala-lang.org/files/archive/spec/2.13/)
+* [Scala Syntax Summary](https://www.scala-lang.org/files/archive/spec/2.13/13-syntax-summary.html)
 
 Development
 -----------