fix: added .env file for default docker setup

.env.docker

@@ -0,0 +1 @@
+DTTMR_DATABASE_URL=postgres://postgres:postgres@172.17.0.1:5432/postgres?sslmode=disable&timezone=utc

Dockerfile

@@ -13,6 +13,7 @@ FROM debian:latest
 
 WORKDIR /app
 
+COPY .env.docker .env
 COPY --from=build /app/server /app/server
 
 EXPOSE 8080