Update PR number from previous broken branch.

CHANGELOG.md

@@ -19,7 +19,7 @@ We use *breaking* word for marking changes that are not backward compatible (rel
 - [#1680](https://github.com/thanos-io/thanos/pull/1680) Add a new `--http-grace-period` CLI option to components which serve HTTP to set how long to wait until HTTP Server shuts down.
 - [#1712](https://github.com/thanos-io/thanos/pull/1712) Rename flag on bucket web component from `--listen` to `--http-address` to match other components.
 - [#1733](https://github.com/thanos-io/thanos/pull/1733) New metric `thanos_compactor_iterations_total` on Thanos Compactor which shows the number of successful iterations.
-- [#1757](https://github.com/thanos-io/thanos/pull/1757) `thanos bucket web` now supports `--web.external-prefix` for proxying on a subpath.
+- [#1758](https://github.com/thanos-io/thanos/pull/1758) `thanos bucket web` now supports `--web.external-prefix` for proxying on a subpath.
 
 ### Fixed