ci: add CircleCI config, remove Travis CI config

.circleci/config.yml

@@ -0,0 +1,21 @@
+version: 2.1
+orbs:
+  node: circleci/node@5.0.3
+alias:
+  - &defaults
+    docker:
+      - image: cimg/node:lts
+    executor: node/default
+jobs:
+  main-job:
+    <<: *defaults
+    steps:
+      - checkout
+      - node/install-packages
+      - run: npm test
+      - run: npx semantic-release
+workflows:
+  version: 2
+  main-workflow:
+    jobs:
+      - main-job

.travis.yml

@@ -1,12 +0,0 @@
-sudo: false
-language: node_js
-notifications:
-  email: false
-node_js:
-- lts/*
-install: npm ci --production=false
-after_success:
-  - npx semantic-release
-branches:
-  except:
-    - /^v\d+\.\d+\.\d+$/