update .gitignore
update .gitignore

- vendor/ is now unused except for vendor/qti_migration_tool
  so ignore it entirely instead of just vendor/gems and vendor/cache
- local sqlite database haven't been used in like nine years
- ignore the redis dump too

Change-Id: Ideb9e3f9d89e90ffa1bd5408b9f95809b5e10047
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/285545
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
Reviewed-by: Mysti Lilla <431d062aff1e8f25416b3a7b732fe6effdb03f9a@instructure.com>
Reviewed-by: Aaron Shafovaloff <d0ee6b99167c663aba7bc3efd806fe8d6cad437b@instructure.com>
QA-Review: Jeremy Stanley <b3f594e10a9edcf5413cf1190121d45078c62290@instructure.com>
Product-Review: Jeremy Stanley <b3f594e10a9edcf5413cf1190121d45078c62290@instructure.com>

instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,sfu/canvas-lms