release: bump release to 3.4.0-rc3

Bump release to 3.4.0-rc3.

Signed-off-by: Anas Nashif <[email protected]>

Author: nashif

VERSION

@@ -2,4 +2,4 @@ VERSION_MAJOR = 3
 VERSION_MINOR = 4
 PATCHLEVEL = 0
 VERSION_TWEAK = 0
-EXTRAVERSION = rc2
+EXTRAVERSION = rc3