Previously, Travis used the latest mono image. By using the same one as
the Docker image, we would have caught the problem in issue #4403
before the changes were merged into the master branch.
After targeting .NET 4.7.1, some users started encountering errors like:
Could not find method '.ctor' due to a type load error: Could not load
file or assembly 'netstandard, Version=2.0.0.0, Culture=neutral,
PublicKeyToken=cc7b13ffcd2ddd51' or one of its dependencies.
assembly:/opt/duplicati/SharpAESCrypt.exe type:SharpAESCrypt
member:(null)
The TencentCOS and Tardigrade backends are built on .NET Standard 2.0,
and it appears that the dependencies can be awoken even if these
backends are not used.
This fixes#4289.
gpatel-fr