Fix typing issue

Author: sventorben

keycloak/openid_client.go

@@ -126,7 +126,7 @@ func (keycloakClient *KeycloakClient) ValidateOpenidClient(ctx context.Context,
 		return fmt.Errorf("validation error: theme \"%s\" does not exist on the server", client.Attributes.LoginTheme)
 	}
 
-    if (client.Attributes.StandardTokenExchangeEnabled && client.PublicClient) {
+    if (client.Attributes.StandardTokenExchangeEnabled == "true" && client.PublicClient) {
 		return fmt.Errorf("validation error: standard token exchange cannot be enabled on public clients")
 	}