Remove vis_encode_type from list of required (#3677)

Author: Ervin T

com.unity.ml-agents/CHANGELOG.md

@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ## [0.15.1-preview] - 2020-03-30
 ### Bug Fixes
  - Raise the wall in CrawlerStatic scene to prevent Agent from falling off. (#3650)
+ - Fixed an issue where specifying `vis_encode_type` was required only for SAC. (#3677)
 
 
 ## [0.15.0-preview] - 2020-03-18

ml-agents/mlagents/trainers/sac/trainer.py

@@ -73,7 +73,6 @@ def __init__(
             "memory_size",
             "model_path",
             "reward_signals",
-            "vis_encode_type",
         ]
 
         self._check_param_keys()