docs: update toolchain requirements

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

Change-Id: I03cb4fd99ecbba412e1b9018de6e6c330374866d
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
diff --git a/docs/getting_started/requirements.rst b/docs/getting_started/requirements.rst
index b69cced..553975f 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 13.2.Rel1 (gcc 13.2):
+been tested with version 13.3.Rel1 (gcc 13.3):
 
 -  `GCC cross-toolchain`_