VERSION: bump for 21.3.0-rc3

Signed-off-by: Eric Engestrom <eric@engestrom.ch>
diff --git a/VERSION b/VERSION
index 560ef00..b8d2c47 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-21.3.0-rc2
+21.3.0-rc3