ci: travis -> GitHub Action

.github/workflows/ci.yaml

@@ -0,0 +1,18 @@
+name: Go package
+
+on: [push, pull_request]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Set up Go
+        uses: actions/setup-go@v4
+        with:
+          go-version: '1.x'
+
+      - name: Test
+        run: go test -v ./...

README.md

@@ -2,7 +2,9 @@
 
 a Go package to interact with arbitrary JSON
 
-[![Build Status](https://secure.travis-ci.org/bitly/go-simplejson.png?branch=master)](http://travis-ci.org/bitly/go-simplejson) [![GoDoc](https://godoc.org/github.com/bitly/go-simplejson?status.svg)](https://godoc.org/github.com/bitly/go-simplejson) [![GitHub release](https://img.shields.io/github/release/bitly/go-simplejson.svg)](https://github.com/bitly/go-simplejson/releases/latest)
+[![Build Status](https://github.com/bitly/go-simplejson/actions/workflows/ci/badge.svg)](https://github.com/bitly/go-simplejson/actions)
+[![GoDoc](https://pkg.go.dev/badge/github.com/bitly/go-simplejson)](https://pkg.go.dev/github.com/bitly/go-simplejson)
+[![GitHub release](https://img.shields.io/github/release/bitly/go-simplejson.svg)](https://github.com/bitly/go-simplejson/releases/latest)
 
 
 ### Importing