Project cannot be build due to JCenter / Bintray dependencies

[svenjacobs]

Trying to build the project currently results in the following error:

./gradlew --no-build-cache --refresh-dependencies assembleDebug

A problem occurred configuring root project 'iosched'.
> Could not resolve all artifacts for configuration ':classpath'.
   > Could not resolve com.diffplug.gradle.spotless:com.diffplug.gradle.spotless.gradle.plugin:3.27.1.
     Required by:
         project :
      > Could not resolve com.diffplug.gradle.spotless:com.diffplug.gradle.spotless.gradle.plugin:3.27.1.
         > Could not get resource 'https://jcenter.bintray.com/com/diffplug/gradle/spotless/com.diffplug.gradle.spotless.gradle.plugin/3.27.1/com.diffplug.gradle.spotless.gradle.plugin-3.27.1.pom'.
            > Could not HEAD 'https://jcenter.bintray.com/com/diffplug/gradle/spotless/com.diffplug.gradle.spotless.gradle.plugin/3.27.1/com.diffplug.gradle.spotless.gradle.plugin-3.27.1.pom'.
               > Read timed out

When accessing the artifact via browser you get a 403 forbidden. It seems the dependency has been removed von JCenter / Bintray.