Update version for v6.1.0-rc3 release

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
diff --git a/VERSION b/VERSION
index 7c5f12f..71858d9 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-6.0.92
+6.0.93