Suppress Either serialization warnings (#2874)

Author: pivovarit

vavr/src/main/java/io/vavr/control/Either.java

@@ -1090,6 +1090,7 @@ final class Left<L, R> implements Either<L, R>, Serializable {
 
         private static final long serialVersionUID = 1L;
 
+        @SuppressWarnings("serial") // Conditionally serializable
         private final L value;
 
         /**
@@ -1153,6 +1154,7 @@ final class Right<L, R> implements Either<L, R>, Serializable {
 
         private static final long serialVersionUID = 1L;
 
+        @SuppressWarnings("serial") // Conditionally serializable
         private final R value;
 
         /**