Modify mlagents for removing server build

[leonard-q]

:star2: Hello! Thanks for contributing JORLDY!

Checklist

Please check if you consider the following items.

• [v] My code follows the style guidelines of this project contributing
• [v] My code follows the naming convention of documentation
• [v] I have commented my code, particularly in hard-to-understand areas
• [v] My changes generate no new warnings or errors

Types of changes

Please describe the types of changes! (ex. Bugfix, New feature, Documentation, ...) Improvement

Test Configuration

• OS: Linux Ubuntu
• Python version: 3.8
• Additional libraries:

Description

Please describe the details of your contribution Modify mlagents env for removing server build. Server build is removed and mlagents envs run with Linux build using no graphics option It can fix the issue #55