15.0 mig maintenance project plan

[dani-xtendoo]

Migration to 15.0 maintentance_project_plan

[dalonsod]

Hello @dani-xtendoo thanks for the contribution! Please follow migration guide at https://github.com/OCA/maintainer-tools/wiki/Migration-to-version-15.0 . At least I see the following things to be fixed:

• Strict migration changes should be placed in a standalone commit "[MIG] $MODULE: Migration to 15.0" (e.g. at least bump version to 15.0.1.0.0), not in pre-commit previous commit.
• Migrated addon should start at 15.0.1.0.0 version.
• Take a look at https://github.com/OCA/maintainer-tools/wiki/Merge-commits-in-pull-requests#mergesquash-the-commits-generated-by-bots-or-weblate and simplify commit history if possible.