Move to github actions

.github/workflows/build.yml

@@ -0,0 +1,17 @@
+name: Build
+on: [push, pull_request]
+jobs:
+  build:
+    strategy:
+      matrix:
+        java-version: [1.8, 11, 14]
+    runs-on: ubuntu-20.04
+    steps:
+      - uses: actions/checkout@v1
+      - uses: actions/setup-java@v1
+        with:
+          java-version: ${{ matrix.java-version }}
+      - uses: eskatos/gradle-command-action@v1.3.2
+        with:
+          gradle-version: wrapper
+          arguments: build javadocJar checkMappings --stacktrace

.travis.yml

@@ -1,14 +0,0 @@
-language: java
-
-jdk:
-  - openjdk8
-  - openjdk11
-  - openjdk14
-
-assemble: true
-install: true
-script:
-  - ./gradlew build javadocJar checkMappings --stacktrace
-
-notifications:
-  email: false