Replace all contexts in tests with go1.24 t.Context()
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Co-authored-by: Giteabot <teabot@gitea.io>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
This PR created a mock webhook server in the tests and added integration
tests for generic webhooks.
It also fixes bugs in package webhooks and pull request comment
webhooks.