[master] move release tag

CHANGES

+	--- 9.12.0b2 released ---
+
 4809.	[port]		Check at configure time whether -latomic is needed
 			for stdatomic.h. [RT #46324]
@@ -7,8 +9,6 @@
 			bytes from the PRNG; this is now used instead of
 			calling isc_rng_random() multiple times. [RT #46230]
-	--- 9.12.0b2 released ---
-
 4806.	[func]		Log messages related to loading of zones are now
 			directed to the "zoneload" logging category.
 			[RT #41640]