Update halfshot/matrix-hookshot Docker tag to v6

[small-hack-renovate]

This PR contains the following updates:

Package	Update	Change
halfshot/matrix-hookshot	major	5.4.1 -> 6.0.0

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Release Notes

matrix-org/matrix-hookshot (halfshot/matrix-hookshot)

v6.0.0

Compare Source

Features

• Add support for setting an expiry time on a webhook. See the documentation on Generic Webhooks for more information. (#​984)
• Support for E2E Encrypted rooms is now considered stable and can be enabled in production. Please see the documentation
  on the requirements for enabling support. (#​989)

Bugfixes

• Fix Challenge Hound activities being duplicated if the cache layer (e.g Redis) goes away. (#​982)

Deprecations and Removals

• Drop support for Node 20 and start supporting Node 22, 23. (#​990)

Internal Changes

• Reduce bundle size of widget. (#​985)
• Don't invoke newsfile CI check for dependabot. (#​987)
• Add devenv development files. (#​993)
• Push Docker images to ghcr.io, and and build an image on each commit. (#​994)
• Retry e2e tests in CI due to container creation flakiness. (#​995)
• Update matrix-bot-sdk to pull in new matrix-rust-sdk. (#​996)

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