release: Zephyr v4.3.0

Set the version to v4.3.0

Signed-off-by: Chris Friedt <cfriedt@tenstorrent.com>
Signed-off-by: Johan Hedberg <johan.hedberg@silabs.com>

Author: cfriedt

VERSION

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