refactor: Update rigid body pr to 4.0 syntax.

[b-butler]

Description

Updates the rigid body tutorial to use version 4.0 syntax.

Resolves: #72

Checklist:

• [x] I have reviewed the Contributor Guidelines.
• [x] I agree with the terms of the HOOMD-blue Contributor Agreement.
• [x] My name is on the list of authors.

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