Bump caddy from 2.7.6-alpine to 2.8.1-alpine

Bumps caddy from 2.7.6-alpine to 2.8.1-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

@@ -10,7 +10,7 @@ COPY . .
 RUN NODE_ENV=production npm run build:with-font
 
 
-FROM caddy:2.7.6-alpine
+FROM caddy:2.8.1-alpine
 EXPOSE 80
 
 COPY build/docker/Caddyfile /etc/caddy/Caddyfile