Update maven-enforcer-plugin to 3.1.0

[php-coder]

Changelogs:

• https://github.com/apache/maven-enforcer/releases/tag/enforcer-3.0.0
• https://github.com/apache/maven-enforcer/releases/tag/enforcer-3.1.0
• https://github.com/apache/maven-enforcer/releases/tag/enforcer-3.2.0
• https://github.com/apache/maven-enforcer/releases/tag/enforcer-3.2.1
• https://github.com/apache/maven-enforcer/releases/tag/enforcer-3.3.0
• https://github.com/apache/maven-enforcer/releases/tag/enforcer-3.4.0
• https://github.com/apache/maven-enforcer/releases/tag/enforcer-3.4.1
• https://github.com/apache/maven-enforcer/releases/tag/enforcer-3.5.0