chore(deps): update caddy docker tag to v2.7.6 (#1718)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

frontend/Dockerfile

@@ -11,7 +11,7 @@ RUN npm ci --ignore-scripts --no-update-notifier --omit=dev && \
 
 # Deploy container
 # Caddy serves static files
-FROM caddy:2.7.5-alpine
+FROM caddy:2.7.6-alpine
 RUN apk add --no-cache ca-certificates
 
 # Copy static files and run formatting