Update forkserver.h

Fix typo
diff --git a/include/forkserver.h b/include/forkserver.h
index 35bc177..50898a0 100644
--- a/include/forkserver.h
+++ b/include/forkserver.h
@@ -43,7 +43,7 @@
   Normal,
   Crash,
   Asan,
-  Timout,
+  Timeout,
   InvalidWriteToPayload,
   Error,
   IoError,