Bump caddy from 2.7.6-alpine to 2.8.0-alpine

Bumps caddy from 2.7.6-alpine to 2.8.0-alpine.

---
updated-dependencies:
- dependency-name: caddy
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Dockerfile

@@ -1,4 +1,4 @@
-FROM caddy:2.7.6-alpine
+FROM caddy:2.8.0-alpine
 
 SHELL ["/bin/ash", "-eo", "pipefail", "-c"]