Bump to v4.0.0 from upstream

* Update matrix-appservice-bridge

Fixes #896

* Drop support for Node 16, default to Node 18

Required for updating to the latest matrix-appservice-bridge

* Update better-sqlite3

Required for Node 20 support

* Update changelog.d/897.removal

Co-authored-by: Will Hunt <will@half-shot.uk>
Signed-off-by: Andrew Ferrazzutti <andrewf@element.io>

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Signed-off-by: Andrew Ferrazzutti <andrewf@element.io>
Co-authored-by: Will Hunt <will@half-shot.uk>