Restore Travis CI. (#131)

* Migrate back to using Travis CI.

* Remove GitHub Actions.

* Add build step before test.

* Remove Node 8 and 12 from matrix.

* Replace GitHub Actions badge with Travis badge.

.travis.yml

@@ -0,0 +1,29 @@
+notifications:
+  email: false
+
+language: node_js
+cache:
+  yarn: true
+node_js:
+  - "10"
+
+matrix:
+  fast_finish: true
+
+install:
+  - yarn install --frozen-lockfile --non-interactive
+
+jobs:
+  include:
+    - stage: Build
+      script:
+        - yarn build
+    - stage: Test
+      script:
+        - yarn build
+        - yarn test
+    - stage: Build Examples
+      script:
+        - yarn build
+        - cd $TRAVIS_BUILD_DIR/examples
+        - for dir in $TRAVIS_BUILD_DIR/examples/*; do (cd "$dir"; yarn; yarn clean; yarn build; cd ../); done

README.md

@@ -2,7 +2,7 @@
 
 [![npm](https://img.shields.io/npm/v/reason-urql.svg)](https://www.npmjs.com/package/reason-urql)
 [![All Contributors](https://img.shields.io/badge/all_contributors-11-orange.svg)](#contributors)
-[![Build Status](https://github.com/FormidableLabs/reason-urql/workflows/reason-urql%20CI/badge.svg)](https://github.com/FormidableLabs/reason-urql/actions)
+[![Build Status](https://travis-ci.org/FormidableLabs/reason-urql.svg?branch=master)](https://travis-ci.org/FormidableLabs/reason-urql)
 [![Maintenance Status][maintenance-image]](#maintenance-status)
 [![Spectrum](https://withspectrum.github.io/badge/badge.svg)](https://spectrum.chat/urql)