fix python->python3 commands

.yamato/standalone-build-test.yml

   variables:
     UNITY_VERSION: {{ config.version }}
   commands:
-    - pip install pyyaml --index-url https://artifactory.prd.it.unity3d.com/artifactory/api/pypi/pypi/simple
+    - python3 -m pip install pyyaml --index-url https://artifactory.prd.it.unity3d.com/artifactory/api/pypi/pypi/simple
-    - python -m pip install unity-downloader-cli --index-url https://artifactory.prd.it.unity3d.com/artifactory/api/pypi/pypi/simple --upgrade
+    - python3 -m pip install unity-downloader-cli --index-url https://artifactory.prd.it.unity3d.com/artifactory/api/pypi/pypi/simple --upgrade
-    - python -u -m ml-agents.tests.yamato.standalone_build_tests
-    - python -u -m ml-agents.tests.yamato.standalone_build_tests --scene=Assets/ML-Agents/Examples/Basic/Scenes/Basic.unity
-    - python -u -m ml-agents.tests.yamato.standalone_build_tests --scene=Assets/ML-Agents/Examples/Bouncer/Scenes/Bouncer.unity
-    - python -u -m ml-agents.tests.yamato.standalone_build_tests --scene=Assets/ML-Agents/Examples/WallJump/Scenes/WallJump.unity
-    - python -u -m ml-agents.tests.yamato.standalone_build_tests --scene=Assets/ML-Agents/TestScenes/TestCompressedGrid/TestGridCompressed.unity
-    - python -u -m ml-agents.tests.yamato.standalone_build_tests --scene=Assets/ML-Agents/TestScenes/TestCompressedTexture/TestTextureCompressed.unity
+    - python3 -u -m ml-agents.tests.yamato.standalone_build_tests
+    - python3 -u -m ml-agents.tests.yamato.standalone_build_tests --scene=Assets/ML-Agents/Examples/Basic/Scenes/Basic.unity
+    - python3 -u -m ml-agents.tests.yamato.standalone_build_tests --scene=Assets/ML-Agents/Examples/Bouncer/Scenes/Bouncer.unity
+    - python3 -u -m ml-agents.tests.yamato.standalone_build_tests --scene=Assets/ML-Agents/Examples/WallJump/Scenes/WallJump.unity
+    - python3 -u -m ml-agents.tests.yamato.standalone_build_tests --scene=Assets/ML-Agents/TestScenes/TestCompressedGrid/TestGridCompressed.unity
+    - python3 -u -m ml-agents.tests.yamato.standalone_build_tests --scene=Assets/ML-Agents/TestScenes/TestCompressedTexture/TestTextureCompressed.unity
   triggers:
     cancel_old_ci: true
     expression: |

.yamato/training-int-tests.yml

   variables:
     UNITY_VERSION: {{ config.version }}
   commands:
-    - pip install pyyaml --index-url https://artifactory.prd.it.unity3d.com/artifactory/api/pypi/pypi/simple
+    - python3 -m pip install pyyaml --index-url https://artifactory.prd.it.unity3d.com/artifactory/api/pypi/pypi/simple
-    - python -m pip install unity-downloader-cli --index-url https://artifactory.prd.it.unity3d.com/artifactory/api/pypi/pypi/simple --upgrade
+    - python3 -m pip install unity-downloader-cli --index-url https://artifactory.prd.it.unity3d.com/artifactory/api/pypi/pypi/simple --upgrade
-    - python -u -m ml-agents.tests.yamato.training_int_tests
+    - python3 -u -m ml-agents.tests.yamato.training_int_tests
-    - 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={{ config.csharp_backcompat_version }}
+    - python3 -u -m ml-agents.tests.yamato.training_int_tests --python=0.16.0
+    - python3 -u -m ml-agents.tests.yamato.training_int_tests --csharp={{ config.csharp_backcompat_version }}
   dependencies:
     - .yamato/standalone-build-test.yml#test_standalone_{{ config.name }}
   triggers:

ml-agents/tests/yamato/yamato_utils.py

         pip_commands += extra_packages
     for cmd in pip_commands:
         pip_index_url = "--index-url https://artifactory.prd.it.unity3d.com/artifactory/api/pypi/pypi/simple"
+        # TODO fix venv activate command for windows (or just don't run it)
-            f"source {venv_path}/bin/activate; python -m pip install -q {cmd} {pip_index_url}",
+            f"source {venv_path}/bin/activate; python3 -m pip install -q {cmd} {pip_index_url}",
             shell=True,
         )
     return venv_path