Bump com.adyen:adyen-java-api-library in /paybylink-example

Bumps [com.adyen:adyen-java-api-library](https://github.com/adyen/adyen-java-api-library) from 20.1.0 to 21.1.0.
- [Release notes](https://github.com/adyen/adyen-java-api-library/releases)
- [Commits](Adyen/adyen-java-api-library@20.1.0...v21.1.0)

---
updated-dependencies:
- dependency-name: com.adyen:adyen-java-api-library
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

paybylink-example/build.gradle

@@ -16,7 +16,7 @@ repositories {
 dependencies {
     implementation 'org.springframework.boot:spring-boot-starter-web'
     testImplementation 'org.springframework.boot:spring-boot-starter-test'
-    implementation 'com.adyen:adyen-java-api-library:20.1.0'
+    implementation 'com.adyen:adyen-java-api-library:21.1.0'
 
 }