Update Dockerfile

Author: techwithjake

Dockerfile

@@ -1,8 +1,8 @@
-FROM caddy:2.7-builder AS builder
+FROM caddy:builder AS builder
 
 RUN xcaddy build \
     --with github.com/caddy-dns/vultr
 
-FROM caddy:2.7-alpine
+FROM caddy:alpine
 
 COPY --from=builder /usr/bin/caddy /usr/bin/caddy