Bump Caddy from 2.7.2 to 2.7.3

ref: https://github.com/caddyserver/caddy/releases/tag/v2.7.3

Author: SlothCroissant

Dockerfile

@@ -1,8 +1,8 @@
-FROM caddy:2.7.2-builder AS builder
+FROM caddy:2.7.3-builder AS builder
 
 RUN xcaddy build \
     --with github.com/caddy-dns/cloudflare
 
-FROM caddy:2.7.2
+FROM caddy:2.7.3
 
 COPY --from=builder /usr/bin/caddy /usr/bin/caddy