Don't exclude static local classes

Author: Marcono1234

gson/src/main/java/com/google/gson/internal/Excluder.java

@@ -199,7 +199,8 @@ private boolean excludeClassChecks(Class<?> clazz) {
           return true;
       }
 
-      if (isAnonymousOrLocal(clazz)) {
+      // Permit static local classes, such as Records (Java 16 feature)
+      if (!isStatic(clazz) && isAnonymousOrLocal(clazz)) {
           return true;
       }