build(deps): bump the java-example-deps group

Bumps the java-example-deps group in /backend/java with 2 updates: [com.fasterxml.jackson.core:jackson-databind](https://github.com/FasterXML/jackson) and com.diffplug.spotless.


Updates `com.fasterxml.jackson.core:jackson-databind` from 2.17.2 to 2.20.1
- [Commits](https://github.com/FasterXML/jackson/commits)

Updates `com.diffplug.spotless` from 6.25.0 to 8.1.0

---
updated-dependencies:
- dependency-name: com.fasterxml.jackson.core:jackson-databind
  dependency-version: 2.20.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: java-example-deps
- dependency-name: com.diffplug.spotless
  dependency-version: 8.1.0
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: java-example-deps
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

backend/java/build.gradle

@@ -1,6 +1,6 @@
 plugins {
     id 'application'
-    id 'com.diffplug.spotless' version '6.25.0'
+    id 'com.diffplug.spotless' version '8.1.0'
 }
 
 group = 'com.sumup.examples'
@@ -12,7 +12,7 @@ repositories {
 
 dependencies {
     implementation 'com.sumup:sumup:0.0.5'
-    implementation 'com.fasterxml.jackson.core:jackson-databind:2.17.2'
+    implementation 'com.fasterxml.jackson.core:jackson-databind:2.20.1'
 }
 
 application {