Flask-iiif

- setup: remove werkzeug pin

- resize: added upscaling params for h & w

Here you can see the full list of changes between each Flask-IIIF
release.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

- api: fix resize of greyscale source images
- bump flask to >=2.0, pin Werkzeug <3.0
- fix deprecated use of ``attachment_filename``

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

- remove custom resizing of GIF

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

- Removes encoding of key, due to incompatibility with python3
- Makes temp folder location regarding the generation of gif files configurable
- Removes upper pinning of Werkzeug
- Closes image after usage to avoid leaking memory during api requests
- Migrates CI to gh-actions
- Updates copyright and contributors

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

- Added missing ``app`` argument for the ``flask_iiif.cache.ImageCache``
constructor.