Fix CI (#57)

Introduces an alternate CI platform (aka Github Actions) since the demise of Travis's free tier.

.github/workflows/test.yml

@@ -0,0 +1,27 @@
+name: Test
+
+on:
+  push:
+  pull_request:
+    branches: [$default-branch]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version:
+          - 8.x
+          - 10.x
+          - 11.x
+          - 20.x
+    steps:
+      - uses: actions/checkout@v3
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v3
+        with:
+          node-version: ${{ matrix.node-version }}
+          cache: "npm"
+      - run: npm i
+      - run: npm test
+      - run: npm run cover

README.md

@@ -2,8 +2,6 @@
 
 Session wrapper around supertest.
 
-[![Build
-Status](https://travis-ci.org/rjz/supertest-session.svg?branch=master)](https://travis-ci.org/rjz/supertest-session)
 [![Coverage
 Status](https://coveralls.io/repos/rjz/supertest-session/badge.png)](https://coveralls.io/r/rjz/supertest-session)