update namespace to reflect MAAS org in galaxy

[cpg1111]

Please include a summary of the change and which issue is fixed.

Fixes https://github.com/maas/ansible-collection/issues/24

Checklist before merging

• [x] Formatting: tox -e format
• [x] Linting: tox -e sanity
• [x] Unit tests: tox -e units

[gilbertc777]

Would it be possible to get this merged and Galaxy updated to resolve the issue? Appreciate it!