Update version to 17.2.0-rc3

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
diff --git a/VERSION b/VERSION
index f309d4a..fd4078e 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-17.2.0-rc2
+17.2.0-rc3