chore(deps): update oven/bun docker tag to v1.2.21 (#1271)

| datasource | package  | from   | to     |
| ---------- | -------- | ------ | ------ |
| docker     | oven/bun | 1.2.20 | 1.2.21 |

Signed-off-by: renovate-sh-app[bot] <219655108+renovate-sh-app[bot]@users.noreply.github.com>
Co-authored-by: renovate-sh-app[bot] <219655108+renovate-sh-app[bot]@users.noreply.github.com>

Author: renovate-sh-app[bot]

actions/lint-pr-title/Dockerfile

@@ -1,7 +1,7 @@
 # This file must be built from the root of the repository.
 # Example: docker build . -f actions/lint-pr-title/Dockerfile
 
-FROM oven/bun:1.2.20@sha256:78f46b81b82d767ee8d729411f6f95089a403c21f17c20a5789df00263d7c5b5 AS base
+FROM oven/bun:1.2.21@sha256:5a2011bf09364b9af658ac1e66f60d08092f4291aeefbff448d58b027734fdd0 AS base
 
 WORKDIR /usr/src/app