Make 0.9.2 release

Merge pull request sktime#688 from jdb78/fix/update-issues

Maintenance issues

Merge pull request sktime#518 from jdb78/feature/better-time-series-docs

feature/better-time-series-docs

Merge pull request sktime#463 from jdb78/maintenance/dependencies-update

Maintenance/dependencies update

Merge pull request sktime#384 from jdb78/feature/release_changelog

Release changelog

Merge pull request sktime#314 from jdb78/fix/gpu-checkpoint-loading

Fix gpu checkpoint loading

Merge pull request sktime#260 from jdb78/fix/transformation

Fix missing output transformation

Merge pull request sktime#254 from jdb78/feature/relase0-8-1

Fix typo

Merge pull request sktime#236 from jdb78/feature/autoregressive-helpers

Add helpers for auto-regressive models

Merge pull request sktime#188 from jdb78/docs/new_model_tutorial

Add tutorial on how to create a new model