chore: upgrade semantic-release (#87)

* chore: upgrade semantic-release

- ignore Node engines on install to avoid failures on Node < 8
- add `travis-deploy-once` and update `.travis.yml` per the [migration guide](https://github.com/semantic-release/semantic-release/releases/tag/v12.0.0)

close #75

* fix: update semantic-release script

.travis.yml

@@ -9,6 +9,8 @@ node_js:
 - "8"
 notifications:
   email: false
+install:
+- yarn install --ignore-engines
 before_script:
 - curl -L https://codeclimate.com/downloads/test-reporter/test-reporter-latest-linux-amd64 > ./cc-test-reporter
 - chmod +x ./cc-test-reporter
@@ -19,7 +21,7 @@ after_script:
 - ./cc-test-reporter after-build --exit-code $TRAVIS_TEST_RESULT
 after_success:
 - yarn build
-- yarn semantic-release
+- npm run travis-deploy-once "npm run semantic-release"
 branches:
   only:
   - master

package.json

@@ -23,7 +23,8 @@
     "lint": "eslint src/**/*.js",
     "test": "npm run lint --silent && npm run test:unit --silent",
     "test:unit": "cross-env NODE_ENV=test LOG4JS_LEVEL='OFF' jest --coverage",
-    "semantic-release": "semantic-release pre && npm publish && semantic-release post"
+    "semantic-release": "semantic-release",
+    "travis-deploy-once": "travis-deploy-once"
   },
   "dependencies": {
     "chalk": "^2.1.0",
@@ -54,8 +55,9 @@
     "jest": "^22.0.1",
     "nodemon": "^1.11.0",
     "prettier": "^1.5.3",
-    "semantic-release": "^11.0.2",
-    "supertest": "^3.0.0"
+    "semantic-release": "^12.4.1",
+    "supertest": "^3.0.0",
+    "travis-deploy-once": "^4.3.4"
   },
   "jest": {
     "coverageReporters": [