Bump latest beta version

Author: leeturner

src/config/versions.ts

@@ -8,7 +8,7 @@
 export const VERSIONS = {
   // WireMock Java versions
   WIREMOCK_STABLE: '3.13.2',
-  WIREMOCK_BETA: '4.0.0-beta.20',
+  WIREMOCK_BETA: '4.0.0-beta.21',
   WIREMOCK_LEGACY: '2.31.0',
 
   GRPC_EXTENSION: '0.11.0'