Update version for v7.0.0-rc4 release

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

VERSION

diff --git a/VERSION b/VERSION
index 80d0afb..9c57137 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-6.2.93
+6.2.94