Upgrade Ubuntu, Grade, Node.js, and Java

User story

As a consumer,
I want the latest versions of all essential software,
in order to avoid known defects and vulnerabilities.

Acceptance criteria

We'll be done when:

• 1. The Docker image builds successfully.
• 2. The image loads with ubuntu@20.04, node@16.x, gradle@7.2, and openjdk-8-jdk@17.
• 3. The image runs w/out defects.