chore(deps): Bump alpine from 3.15.3 to 3.15.4

Bumps alpine from 3.15.3 to 3.15.4.

---
updated-dependencies:
- dependency-name: alpine
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

Dockerfile

@@ -1,6 +1,6 @@
 FROM nginxproxy/docker-gen:0.8.4 AS docker-gen
 
-FROM alpine:3.15.3
+FROM alpine:3.15.4
 
 ARG GIT_DESCRIBE
 ARG ACMESH_VERSION=2.9.0