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

Bumps nginxinc/nginx-unprivileged from `d532ff0` to `73c290d`.

---
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:1.27.3-alpine@sha256:d532ff0a77e1160527e84fc95f2dfa60b01b90241e9a78eb0300999fd299ce7d
+FROM nginxinc/nginx-unprivileged:1.27.3-alpine@sha256:73c290de1b627ecc4dbc4e58ccdc78d6c0d3f6c06baf4e3e09615bcabd643e0a
 
 # Arguments that can be passed at build time
 ARG COMMIT_SHA=unknown