Incompatible with gradle 7+

[kbjerke]

https://github.com/swagger-api/swaggerhub-gradle-plugin/blob/2d32c3777083af4b2269c60b624f8ff82150e5d4/src/main/java/io/swagger/swaggerhub/tasks/DownloadTask.java#L83-L87

These changes are not released in a new version of the gradle plugin, and therefore are incompatible with newer versions of gradle, complaining about field incorrectly marked as @Optional

Please release new version.

[Bryksin]

Confirm
Gradle v7.5.1 - fails with:

A problem was found with the configuration of task ':swaggerhubDownload' (type 'DownloadTask').
  - In plugin 'io.swagger.swaggerhub' type 'io.swagger.swaggerhub.tasks.DownloadTask' property 'port' of type int shouldn't be annotated with @Optional.
    
    Reason: Properties of primitive type cannot be optional.

Had to downgrade Gradle to v6.9.3

[HugoMario]

It seems this issue was solved by #12 PR
and the specific fix for the compatibility error can be viewed at: 3f6f211

A new release is needed to have the plugin that works with Gradle 7+