feat: add autoware_utils main branch to autoware-nightly.repos (autowarefoundation#5731)

Signed-off-by: Ryohsuke Mitsudome <ryohsuke.mitsudome@tier4.jp>

Author: mitsudome-r

autoware-nightly.repos

@@ -11,6 +11,10 @@ repositories:
     type: git
     url: https://github.com/autowarefoundation/autoware.core.git
     version: main
+  core/autoware_utils: # TODO(mitsudome-r): Remove this repository entry when https://github.com/autowarefoundation/autoware/pull/5700 is merged.
+    type: git
+    url: https://github.com/autowarefoundation/autoware_utils.git
+    version: main
   universe/autoware.universe:
     type: git
     url: https://github.com/autowarefoundation/autoware.universe.git