build(deps): bump nginxinc/nginx-unprivileged in /docker

Bumps nginxinc/nginx-unprivileged from 1.27.2-alpine to 1.27.3-alpine.

---
updated-dependencies:
- dependency-name: nginxinc/nginx-unprivileged
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

docker/Dockerfile.alpine

@@ -1,4 +1,4 @@
-FROM nginxinc/nginx-unprivileged:1.27.2-alpine@sha256:dbe45a35774e1663be48f0e383e294fffcdf1d97dadfd2be689ab4569ab6abb5
+FROM nginxinc/nginx-unprivileged:1.27.3-alpine@sha256:8d20086fe28cc02b51192c61707dda64ce6eaf1d08e47e6a60daa5f8ea9ab3e7
 
 # Arguments that can be passed at build time
 ARG COMMIT_SHA=unknown