Update to oauth2-oidc-sdk 8.23.1

Closes gh-231

gradle/dependency-management.gradle

@@ -25,7 +25,7 @@ dependencyManagement {
 	}
 
 	dependencies {
-		dependency "com.nimbusds:oauth2-oidc-sdk:latest.release"
+		dependency "com.nimbusds:oauth2-oidc-sdk:8.23.1"
 		dependency "com.nimbusds:nimbus-jose-jwt:latest.release"
 		dependency "javax.servlet:javax.servlet-api:4.+"
 		dependency 'junit:junit:latest.release'