chore(deps): bump coder/coder from v2.18.4 to v2.18.5 in /heroku

Bumps [coder/coder](https://github.com/coder/coder) from v2.18.4 to v2.18.5.
- [Release notes](https://github.com/coder/coder/releases)
- [Changelog](https://github.com/coder/coder/blob/main/release.key)
- [Commits](coder/coder@v2.18.4...v2.18.5)

---
updated-dependencies:
- dependency-name: coder/coder
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

heroku/Dockerfile

@@ -1,3 +1,3 @@
-FROM ghcr.io/coder/coder:v2.18.4
+FROM ghcr.io/coder/coder:v2.18.5
 ENV CODER_TELEMETRY_INSTALL_SOURCE=heroku
 ENTRYPOINT []