Add support for Strapi version 4

[dmitrybelyakov]

It's a very useful library, it would be nice if we could use it with Strapi v4.

[galago]

yes please, I wanna migrate to v4 and I need this library working.

[chris-schra]

just created a PR with a quick fix:
#48

[aperron]

PR merged. see v2.0.14