Adding one module after Strapi Docker setup

General
1

I’d like to add the strapi-plugin-bootstrap-admin-user plugin after Strapi has finished installing in Docker.
I’m trying to add it at the entrypoint since I suppose that Strapi should be done installing at that point.

docker-compose.yml:

version: "3.8"
services:
  postgres:
    image: postgres
    environment:
      POSTGRES_DB: strapi
      POSTGRES_USER: strapi
      POSTGRES_PASSWORD: strapi
    volumes:
      - ./data/postgres:/var/lib/postgresql/data

  strapi:
    image: strapi/strapi
    environment:
      DATABASE_CLIENT: postgres
      DATABASE_NAME: strapi
      DATABASE_HOST: postgres
      DATABASE_PORT: 5432
      DATABASE_USERNAME: strapi
      DATABASE_PASSWORD: strapi
      STRAPI_TELEMETRY_DISABLED: "True"
    volumes:
      - ./server/strapi/app:/srv/app
    ports:
      - '1337:1337'
    depends_on:
      - postgres
    working_dir: '/srv/app'
    entrypoint: bash -c 'npm install strapi-plugin-bootstrap-admin-user && /bin/sh /usr/local/bin/docker-entrypoint.sh'

Unfortunately I end up with an error:

strapi_1    | npm WARN saveError ENOENT: no such file or directory, open '/srv/app/package.json'
strapi_1    | npm notice created a lockfile as package-lock.json. You should commit this file.
strapi_1    | npm WARN enoent ENOENT: no such file or directory, open '/srv/app/package.json'
strapi_1    | npm WARN app No description
strapi_1    | npm WARN app No repository field.
strapi_1    | npm WARN app No README data
strapi_1    | npm WARN app No license field.
strapi_1    | 
strapi_1    | + strapi-plugin-bootstrap-admin-user@1.0.8
strapi_1    | added 1 package from 1 contributor and audited 1 package in 1.405s
strapi_1    | found 0 vulnerabilities
strapi_1    | 
strapi_1    | Starting your app...
docker-sveltekit_strapi_1 exited with code 0

Am I doing it wrong? Would it be better to create a Dockerfile?

Thanks!