re-enable backwards compat tests

.yamato/training-int-tests.yml

     # Backwards-compatibility tests.
     # If we make a breaking change to the communication protocol, these will need
     # to be disabled until the next release.
-    # - python -u -m ml-agents.tests.yamato.training_int_tests --python=0.15.0
-    # - python -u -m ml-agents.tests.yamato.training_int_tests --csharp=0.15.0
+    - python -u -m ml-agents.tests.yamato.training_int_tests --python=0.16.0
+    - python -u -m ml-agents.tests.yamato.training_int_tests --csharp=1.0.0
   dependencies:
     - .yamato/standalone-build-test.yml#test_mac_standalone_{{ editor.version }}
   triggers:

ml-agents/tests/yamato/yamato_utils.py

     if csharp_version is None:
         return
 
+    csharp_tag = f"com.unity.ml-agents_{csharp_version}"
-        subprocess.check_call(
-            f"git checkout {csharp_version} -- {csharp_dir}", shell=True
-        )
+        subprocess.check_call(f"git checkout {csharp_tag} -- {csharp_dir}", shell=True)
 
 
 def undo_git_checkout():