quiet-transaction: Remove unnecessary finalize

This hasn't done anything useful since 0978826c: it just takes a
new ref to the installation, and then releases that ref without doing
anything with it. Detected by scan-build.

Signed-off-by: Simon McVittie <smcv@collabora.com>
This commit is contained in:
Internal Server Error - Gitea: Git with a cup of tea
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Gitea Version: 1.28.0+dev-477-g8b6ad49a5f