Mozilla-version

Added
* 128 is the next ESR major version

Removed
* Support for python < 3.8

Added
* Support for python 3.12

Fixed
* Thunderbird `38.0.1esr` was wrongly considered both a major version and a ESR one.

Added
* `MobileVersion` also new properties: `is_major`, `is_stability`, `is_development`.
* `ShipItVersion`, a class that subclasses `BaseVersion`.

Changed
* `GeckoVersion` and `MobileVersion` now inherit `ShipItVersion` (and still `BaseVersion`, indirectly).

Added
* `GeckoVersion` exposes new properties: `is_major`, `is_stability`, `is_development`.

Added
* Version classes are now exported at the top level of the `mozilla_version` module.

Removed
* Support for python < 3.7

Added
* 115 is the next ESR major version