Swagger Codegen Generators v1.0.39

See also https://github.com/swagger-api/swagger-codegen/releases/tag/v3.0.42

What's Changed

• added okhttp4-gson ibrary for java generator by @HugoMario in #1115
• Fixed errors on generators by @HugoMario in #1118
• PHP 7.4 Support by @HugoMario in #1119
• Kotlin Generated code update by @HugoMario in #1122
• added comment in empty template to fix null bytes error by @HugoMario in #1125
• JDK 11+ - update dependencies by @frantuma in #1126

Full Changelog: v1.0.38...v1.0.39