cast time penalty to float (#5424)

Project/Assets/ML-Agents/Examples/Soccer/Scripts/SoccerEnvController.cs

     {
         if (scoredTeam == Team.Blue)
         {
-            m_BlueAgentGroup.AddGroupReward(1 - m_ResetTimer / MaxEnvironmentSteps);
+            m_BlueAgentGroup.AddGroupReward(1 - (float)m_ResetTimer / MaxEnvironmentSteps);
-            m_PurpleAgentGroup.AddGroupReward(1 - m_ResetTimer / MaxEnvironmentSteps);
+            m_PurpleAgentGroup.AddGroupReward(1 - (float)m_ResetTimer / MaxEnvironmentSteps);
             m_BlueAgentGroup.AddGroupReward(-1);
         }
         m_PurpleAgentGroup.EndGroupEpisode();