Intermittent issue when downloading the ets-10 test suite

[isabelrios]

Under investigation. It has happened a few times that the test suite finishes in travis with a BUILD FAILURE due to error:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-site-plugin:3.4:jar (site-package) on project ets-sta10: SiteToolException: The site descriptor cannot be resolved from the repository: ArtifactResolutionException: Unable to locate site descriptor: Could not transfer artifact org.opengis.cite:ets-common:xml:site_en:6 from/to sonatype-apache (https://repository.apache.org/releases/): Connect to repository.apache.org:443 [repository.apache.org/207.244.88.143] failed: Connection timed out

This has not been reproduced locally, only in travis so far.