Mizdb-watchlist

- fix Django requirements being too strict (was ">4", should be ">=4.2")

- enable overriding watchlist manager classes via settings
- add `get_object_text` hook to WatchlistViewMixin: use this to dictate the text to be displayed for a watchlist item on
the watchlist overview

- add missing `watchlist_init.js` to admin watchlist template

- get CSRF value from cookie if not using token

- reworked toggle button:
- toggling the toggle button now only toggles `on-watchlist` CSS class
(was also toggling `text-primary` and `text-success`)
- added `watchlist_toggle.css`
- `toggle_button` template tag now accepts `classes` argument for providing own
CSS classes
- toggle button template no longer includes CSS classes
`btn btn-link text-decoration-none` by default

- reworked how watchlist buttons are initialized:
- `watchlist.js` no longer adds click event handlers when the page has been loaded
- `watchlist.js` now exposes several init functions that must be called to
add the click event handlers for their respective
button: `initToggleButton`, `initRemoveButton`, `initRemoveAllButton`, `initButton`
- the exposed functions allow users to add callback functions that will be called
after the response from the server was handled
- added `watchlist_init.js` that initializes all watchlist buttons on a page

- tweak watchlist overview template and CSS
- toggle button template tag and watchlist link template tag now silence
NoReverseMatch exceptions when URL name cannot be reversed

- fix repository URL in pyproject.toml