`./gradlew ide` fails due to HTTP code 403 from `dl.bintray.com`

Here is the output:
```
$ ./gradlew ide
Downloading https://services.gradle.org/distributions/gradle-6.7-bin.zip
.........10%..........20%..........30%..........40%..........50%.........60%..........70%..........80%..........90%..........100%

Welcome to Gradle 6.7!

Here are the highlights of this release:
- File system watching is ready for production use
- Declare the version of Java your build requires
- Java 15 support

For more details see https://docs.gradle.org/6.7/release-notes.html

Starting a Gradle Daemon (subsequent builds will be faster)

> Configure project :target.p2
p2AsMaven eclipse-deps is dirty.
Initalizing maven group eclipse-deps from p2
Only needs to be done once, future builds will be much faster
p2AsMaven eclipse-deps installing from p2

> Configure project :
Installing p2 bootstrap 4.7.2...
FAILURE: Build failed with an exception.

* Where:
Build file '/home/marten/gradle-and-eclipse-rcp/build.gradle' line: 58

* What went wrong:
A problem occurred evaluating root project 'gradle-and-eclipse-rcp'.
> A problem occurred configuring project ':target.p2'.
> https://dl.bintray.com/diffplug/opensource/com/diffplug/gradle/goomph-p2-bootstrap/4.7.2/goomph-p2-bootstrap.zip
received http code 403
Forbidden!

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 1m 3s

$ java -version
openjdk version "11.0.11" 2021-04-20
OpenJDK Runtime Environment (build 11.0.11+9)
OpenJDK 64-Bit Server VM (build 11.0.11+9, mixed mode)
```