docs: update toolchain requirements documentation

TF-A tests have been verified with the latest toolchain verison
12.3.Rel1. Henceforth the requirements are updated.

Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
Change-Id: I4c4c996862f0ca11805002128097c3d1c91d0809
diff --git a/docs/getting_started/requirements.rst b/docs/getting_started/requirements.rst
index ca1a0c5..74b3e3d 100644
--- a/docs/getting_started/requirements.rst
+++ b/docs/getting_started/requirements.rst
@@ -28,7 +28,7 @@
 Note that at least Python 3.8 is required.
 
 Download and install the GNU cross-toolchain from Arm. The TF-A Tests have
-been tested with version 12.2.Rel1 (gcc 12.2):
+been tested with version 12.3.Rel1 (gcc 12.3):
 
 -  `GCC cross-toolchain`_