I've bumped it to V5 + typescript, added support for private buckets, s3 & minio. Only tested on self hosted Minio though.
I've also opened a PR, so hopefully this will be merged at some point.

In the meantime, you might want to do this in your package.json :
"strapi-plugin-placeholder": "github:Gaylord-Julien/strapi-plugin-placeholder#main",

Then in plugins.ts :

  "strapi-plugin-placeholder": {
    enabled: true,
    resolve: "./node_modules/strapi-plugin-placeholder",
    config: {
      endpoint: env("MINIO_ENDPOINT"),
      accessKey: env("MINIO_ACCESS_KEY"),
      secretKey: env("MINIO_SECRET_KEY"),
      bucket: env("MINIO_BUCKET"),
      forcePathStyle: true,
    },
  },