dependabot: bump de.undercouch.download from 5.3.0 to 5.6.0 (#719)

Bumps [de.undercouch.download](https://github.com/michel-kraemer/gradle-download-task) from 5.3.0 to 5.6.0.
- [Release notes](https://github.com/michel-kraemer/gradle-download-task/releases)
- [Commits](michel-kraemer/gradle-download-task@5.3.0...5.6.0)

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

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

Author: dependabot[bot]

build.gradle

@@ -33,7 +33,7 @@ buildscript {
 }
 
 plugins {
-    id "de.undercouch.download" version "5.3.0"
+    id "de.undercouch.download" version "5.6.0"
     id 'com.netflix.nebula.ospackage' version "11.10.1"
     id 'java-library'
     id "com.diffplug.spotless" version "6.25.0"