0.9.0 release

New features:

- add private builds
- inputvalidation: TuxtriggerConfiguration: refactor configure logic
- inputvalidation: SquadConfig: make it possible to override is_public

Bug fixes:

- fix: pages deploy without repository job
- set pages deploy only for tags
- constants: SQUAD_CONFIG: threshold: use a list
- repository: always run create_or_update_project
- inputvalidation: check for squad credentials
- main: handle known exceptions gracefully
- tuxintegration: don't fail if SQUAD connection error

Documentation updates:

- add index.md file to docs path
- doc: remove deb and rpm install instructions
- doc: Improved run instructions
- docs: run.md: fix typo