Add support to Keycloak 15.0.2

[JoseGoncalves]

I'm using Keycloak 15.0.2 and for that needed to to update peerDependencies in vue-keycloak:

JoseGoncalves/vue-keycloak@e444abb

Can vue-keycloak be updated to support the latest Keycloak?

[JoseGoncalves]

As this repo seems to be unmaintained, I've forked it and keeped it in sync with latest Keycloak versions at JoseGoncalves/vue-keycloak.