Resolve "Compatibility matrix is incorrect"

General MR

Summary

Community feedback indicates plugin version 3.2.1 is not compatible with keycloak 21.0.2 as currently indicated, however it is compatible with keycloak 21.1.2. Update compatibility matrix to reflect this.

Relevant logs/screenshots

(Include any relevant logs/screenshots)

Linked Issue

Closes #35 (closed)

Upgrade Notices

N/A