Update LArCustomSolidExtension to git url without redirect

I run into issues when trying to build the ATLAS externals in a singularity container. Here, the recursive clone step in CMake, git has to follow a redirect from

https://gitlab.cern.ch/SolidExtensions/LArCustomSolidExtension to https://gitlab.cern.ch/SolidExtensions/LArCustomSolidExtension.git

which fails, I believe due to the singularity environment.

I believe updating the submodule git url to the redirect target should be safe to do.

changed the description

Hi @pagessin , thanks for this MR. It looks fine to me. Tagging @boudreau Cheers, Marilena

merged

mentioned in commit cccce794