Refine docker-compose.yml:

1. use short volume bind syntax.
2. fix postgres volume issue.
   check luckyframework#798.
3. Add POSTGRES_DB env for clarify,
   check luckyframework/lucky#1791 (reply in thread)
4. Add crystal build cache into volume for better performance.

src/web_app_skeleton/docker-compose.yml

@@ -1,4 +1,4 @@
-version: '3.8'
+version: "3.8"
 services:
   lucky:
     build:
@@ -8,15 +8,10 @@ services:
       DATABASE_URL: postgres://lucky:password@postgres:5432/lucky
       DEV_HOST: "0.0.0.0"
     volumes:
-      - type: bind
-        source: .
-        target: /app
-      - type: volume
-        source: node_modules
-        target: /app/node_modules
-      - type: volume
-        source: shards_lib
-        target: /app/lib
+      - .:/app
+      - node_modules:/app/node_modules
+      - shards_lib:/app/lib
+      - build_cache:/root/.cache/crystal
     depends_on:
       - postgres
     ports:
@@ -30,10 +25,9 @@ services:
     environment:
       POSTGRES_USER: lucky
       POSTGRES_PASSWORD: password
+      POSTGRES_DB: lucky
     volumes:
-      - type: volume
-        source: postgres_data
-        target: /var/lib/postgresql
+      - postgres_data:/var/lib/postgresql/data
     ports:
       # The postgres database container is exposed on the host at port 6543 to
       # allow connecting directly to it with postgres clients. The port differs
@@ -46,3 +40,4 @@ volumes:
   postgres_data:
   node_modules:
   shards_lib:
+  build_cache: