Update .gitmodules

[jorgtied]

googletest seems to have changed from master to main. This breaks submodule initialization (at least for me)

[snukky]

Thanks for reporting this. I think this change should not be needed for the current setup: third_party/googletest points to a specific commit 0fc5466, which still exists in the origin/HEAD - the default branch if none specified. I couldn't reproduce the issue with the current marian-dev using git 2.25.1. Did you update the submodule manually or use a marian fork that may have different setup of submodules?

[jorgtied]

OK - good to know. I have marian-dev as a sub-module in one of my projects and I got a problem for some strange reason. I need to check what happened there. Thanks for taking the time to check it ...