ci: migrate to GitHub actions (#197)

Author: tjkandala

.github/workflows/build.yml

@@ -0,0 +1,24 @@
+name: build
+
+on: [push, pull_request]
+
+env:
+  FORCE_COLOR: 3
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Use Node.js
+        uses: actions/setup-node@v1
+        with:
+          node-version: '14.7.0'
+      - run: yarn --frozen-lockfile
+      - run: yarn prettier-check
+      - run: yarn tslint
+      - run: yarn typecheck
+      - run: yarn build
+      - run: yarn cover
+      - run: yarn nyc report --reporter json
+      - run: 'bash <(curl -s https://codecov.io/bash)'

.travis.yml

@@ -1,6 +1,6 @@
 # sourcegraph-git-extras
 
-[![build](https://travis-ci.org/sourcegraph/sourcegraph-git-extras.svg?branch=master)](https://travis-ci.org/sourcegraph/sourcegraph-git-extras)
+[![master build status](https://img.shields.io/github/workflow/status/sourcegraph/sourcegraph-git-extras/build/master?logo=github)](https://github.com/sourcegraph/sourcegraph-git-extras/actions?query=branch%3Amaster)
 [![codecov](https://codecov.io/gh/sourcegraph/sourcegraph-git-extras/branch/master/graph/badge.svg?token=c3KpMf1MaY)](https://codecov.io/gh/sourcegraph/sourcegraph-git-extras)
 [![code style: prettier](https://img.shields.io/badge/code_style-prettier-ff69b4.svg)](https://github.com/prettier/prettier)