Use Github Actions workflow for PRs and remove Travis

Closes gh-8716

.github/workflows/pr-build-workflow.yml

@@ -0,0 +1,22 @@
+name: PR Build
+
+on: pull_request
+
+jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up JDK
+        uses: actions/setup-java@v1
+        with:
+          java-version: '8'
+      - name: Cache Gradle packages
+        uses: actions/cache@v2
+        with:
+          path: ~/.gradle/caches
+          key: ${{ runner.os }}-gradle-${{ hashFiles('**/*.gradle') }}
+      - name: Build with Gradle
+        run: ./gradlew clean build --continue

.travis.yml

@@ -1,16 +0,0 @@
-language: java
-
-jdk:
-  - openjdk8
-
-os:
-  - linux
-
-before_cache:
-  - rm -f $HOME/.gradle/caches/modules-2/modules-2.lock
-cache:
-  directories:
-    - $HOME/.gradle/caches/
-    - $HOME/.gradle/wrapper/
-
-script: ./gradlew build --refresh-dependencies --no-daemon --continue

README.adoc

@@ -1,7 +1,5 @@
 image::https://badges.gitter.im/Join%20Chat.svg[Gitter,link=https://gitter.im/spring-projects/spring-security?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge]
 
-image:https://travis-ci.org/spring-projects/spring-security.svg?branch=master["Build Status", link="https://travis-ci.org/spring-projects/spring-security"]
-
 = Spring Security
 
 Spring Security provides security services for the https://docs.spring.io[Spring IO Platform]. Spring Security 5.0 requires Spring 5.0 as