Add Github Actions workflow

.github/workflows/maven.yml

+# This workflow will build a Java project with Maven
+# For more information see: https://help.github.com/actions/language-and-framework-guides/building-and-testing-java-with-maven
+
+name: Java CI with Maven
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-18.04
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up JDK 11
+      uses: actions/setup-java@v1
+      with:
+        java-version: 11
+    - name: Build with Maven
+      run: mvn clean verify

.travis.yml

-language: java
-dist: bionic
-jdk:
-- openjdk11
-sudo: required
-
-env:
-  global:
-  - secure: "DCpazS3nkLnter3sguXEAS2fC/1ZWNfM+XLyif9MfNFxlZdpni2vCD/jA0Rdpga8puQWHNVLyAec+RPFH/2qSmJ1c1UTV5MaLv8tPqwUX0VFA+1I6XoSv6oX4ldHTBWHEWqQHkRFOLoil0h0edc0tTOWQwXF8U+DLAB+HkRb4gw="
-
-services:
-- xvfb
-
-addons:
-  sonarcloud:
-    organization: "iluwatar"
-    token:
-      secure: "FpHwMYPMkdWU6CeIB7+O3qIeIM4vJMp47UjkKK53f0w0s6tPZofZZkab+gcL2TqKSil7sFVB/AQXU1cUubflRszwcLbNsc8H2yFehD79o0o0Mqd1Dd5ip/q0KQbHkkln+InFlVLfvrLB4Xd4mlQVxbGhqpULBhXjKzFzQlRFcuU="
-script:
-  # Because of Travis security restrictions, SonarCloud analysis cannot be run on pull requests originated from forks
-  # See https://docs.travis-ci.com/user/pull-requests/#pull-requests-and-security-restrictions
-  - 'if [ "$TRAVIS_PULL_REQUEST" != "false" ]; then mvn clean verify; fi'
-  - 'if [ "$TRAVIS_PULL_REQUEST" = "false" ]; then mvn clean verify sonar:sonar -Dsonar.projectKey=iluwatar_java-design-patterns -Dsonar.host.url=https://sonarcloud.io; fi'
-
-after_success:
-- bash update-website.sh
-
-notifications:
-  email:
-    - iluwatar@gmail.com
-  webhooks:
-    urls:
-      - https://webhooks.gitter.im/e/3319623945358a093a6f
-    on_success: change  # options: [always|never|change] default: always
-    on_failure: always  # options: [always|never|change] default: always
-    on_start: never     # options: [always|never|change] default: always