remove postgres user creation in Dockerfile

Dockerfile

@@ -5,11 +5,7 @@ USER root
 # Install PostgreSQL and necessary dependencies
 RUN apk update && apk add --no-cache \
     postgresql \
-    postgresql-contrib \
-    shadow
-
-# Create postgres user and group
-RUN addgroup -S postgres && adduser -S -G postgres postgres
+    postgresql-contrib
 
 # Set up environment variables
 ENV DATABASE_URL=postgresql://postgres:postgres@localhost:5432/postgres