Bump de.undercouch.download from 5.5.0 to 5.6.0 (#401)

Bumps [de.undercouch.download](https://github.com/michel-kraemer/gradle-download-task) from 5.5.0 to 5.6.0.
- [Release notes](https://github.com/michel-kraemer/gradle-download-task/releases)
- [Commits](michel-kraemer/gradle-download-task@5.5.0...5.6.0)

---
updated-dependencies:
- dependency-name: de.undercouch.download
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

agent/build.gradle

@@ -5,7 +5,7 @@ plugins {
     id "signing"
     id "org.unbroken-dome.test-sets" version "4.0.0"
     id 'me.champeau.gradle.japicmp' version '0.4.2' apply false
-    id 'de.undercouch.download' version '5.5.0' apply false    
+    id 'de.undercouch.download' version '5.6.0' apply false    
 }
 
 import me.champeau.gradle.japicmp.JapicmpTask