fix liquid syntax.

.yamato/com.unity.ml-agents-test.yml

     {% if platform.name == "win" %}
     - upm-ci package test -u "C:\build\output\Unity-Technologies\ml-agents\.Editor" --package-path com.unity.ml-agents {{ editor.coverageOptions }}
     {% else %}
-    - upm-ci package test -u editor.version --package-path com.unity.ml-agents {{ editor.coverageOptions }}
+    - upm-ci package test -u {{ editor.version }} --package-path com.unity.ml-agents {{ editor.coverageOptions }}
     {% endif %}
     - python3 ml-agents/tests/yamato/check_coverage_percent.py upm-ci~/test-results/ {{ editor.minCoveragePct }}
   artifacts: