chore: Update year in licence.

feat: Bump SDK version to `3.1.0` and add lints.

misc: Update licence bearer and links.

feat: Remove `avoid_equals_and_hash_code_on_mutable_classes`.

feat: Remove `strict-raw-types` due to it making code look bloated.

feat: Bump SDK version to `3.0.0` and add lints.

chore!: Relicense as `MIT` from `AGPL-3.0`.

fix: Wrong option (`strong-mode` -> `language`).

feat: Bump SDK version to `2.19.0` and add lints.

feat: Bump SDK version to `2.18.0` and add new lints.