Jitpack packages should be generated at release time

[jcpitre]

Describe the problem

In #1473 there was a problem for jitpack to build release 4.1.0 of the validator jars.
We should make sure jitpack builds the jars properly as part of the release.

Proposed solution

We need to have a dummy build with have this in build.gradle:

repositories {
   ...
    maven { url 'https://jitpack.io' }
    mavenCentral() // <2>
}

dependencies {
   ...
    implementation 'com.github.MobilityData:gtfs-validator:v4.1.0'
}

Adjust for the release tag (v4.1.0 in this case)
The project could have a simple "Hello World" java class.

This dummy build has to be executed as part of the release, ideally from a Github action.
Errors running the build should be reported and maybe block the release.

Alternatives you've considered

No response

Additional context

No response

[emmambd]

Closing since jitpack has been replaced with Maven at #1596