Migrate to GitHub Actions (purescript#54)

* Migrate to GitHub Actions and update installation instructions.

* Censor user-defined warnings to accommodate MonadZero deprecation

.github/workflows/ci.yml

@@ -0,0 +1,31 @@
+name: CI
+
+on: push
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - uses: purescript-contrib/setup-purescript@main
+        with:
+          purescript: "0.14.0-rc3"
+
+      - uses: actions/setup-node@v1
+        with:
+          node-version: "12"
+
+      - name: Install dependencies
+        run: |
+          npm install -g bower
+          npm install
+          bower install --production
+
+      - name: Build source
+        run: npm run-script build
+
+      - name: Run tests
+        run: |
+          bower install
+          npm run-script test --if-present

.gitignore

@@ -1,6 +1,6 @@
 /.*
 !/.gitignore
-!/.travis.yml
+!/.github/
 /bower_components/
 /node_modules/
 /output/

README.md

@@ -1,14 +1,14 @@
 # purescript-maybe
 
 [![Latest release](http://img.shields.io/github/release/purescript/purescript-maybe.svg)](https://github.com/purescript/purescript-maybe/releases)
-[![Build status](https://travis-ci.org/purescript/purescript-maybe.svg?branch=master)](https://travis-ci.org/purescript/purescript-maybe)
+[![Build status](https://github.com/purescript/purescript-maybe/workflows/CI/badge.svg?branch=master)](https://github.com/purescript/purescript-maybe/actions?query=workflow%3ACI+branch%3Amaster)
 
 Optional values. `Maybe` is often used to capture failures and in cases where nullable values might otherwise have been used in other languages.
 
 ## Installation
 
 ```
-bower install purescript-maybe
+spago install maybe
 ```
 
 ## Documentation

package.json

@@ -2,7 +2,7 @@
   "private": true,
   "scripts": {
     "clean": "rimraf output && rimraf .pulp-cache",
-    "build": "pulp build -- --censor-lib --strict"
+    "build": "pulp build -- --censor-lib --strict --censor-codes='UserDefinedWarning'"
   },
   "devDependencies": {
     "pulp": "^15.0.0",