renovate/lib/modules/versioning/unity3d-packages

Unity versioning follow semantic versioning, followed optionally by -exp.# or -pre.#: https://docs.unity3d.com/Manual/upm-lifecycle.html

Examples:

• 0.1.2
• 1.2.3-exp.1
• 1.3.0-pre.1
• 1.4.0-preview.1