west.yml: Lock the manifest for the v2023.10.0 release

Lock the versions of libmetal, open-amp, and openamp-zephyr-modules to
their v2023.10.0 tags.

This commit is also the first on the v2023.10 branch which will be updated
if there is every another v2023.10.x release.

Signed-off-by: Bill Mills <bill.mills@linaro.org>

west.yml

@@ -22,13 +22,13 @@ manifest:
     # as we use the same names as in the zephyr manifest,
     # our definitions eclipse their's
     - name: libmetal
-      revision: main
+      revision: v2023.10.0
 
     - name: open-amp
-      revision: main
+      revision: v2023.10.0
 
     # however, our version does not have the zephyr module glue
     # so bring in our custom version that integrates both libraries
     # as a single zephyr module
     - name: openamp-zephyr-modules
-      revision: main
+      revision: v2023.10.0