update GGML submodule url

[danemadsen]

The submodule url you have set is throwing the error below when cloning / updating submodules

git submodule update --init --recursive
Submodule 'benchmark' (https://github.com/google/benchmark.git) registered for path 'benchmark'
Submodule 'ggml' ([email protected]:maxilevi/ggml.git) registered for path 'ggml'
Submodule 'highway' (https://github.com/google/highway.git) registered for path 'highway'
Submodule 'ios-cmake' (https://github.com/leetal/ios-cmake.git) registered for path 'ios-cmake'
Cloning into '/Users/danemadsen/vits.cpp/benchmark'...
Cloning into '/Users/danemadsen/vits.cpp/ggml'...
The authenticity of host 'github.com (4.237.22.38)' can't be established.
ED25519 key fingerprint is SHA256:+DiY3wvvV6TuJJhbpZisF/zLDA0zPMSvHdkr4UvCOqU.
This key is not known by any other names.
Are you sure you want to continue connecting (yes/no/[fingerprint])? y
Please type 'yes', 'no' or the fingerprint: yes
Warning: Permanently added 'github.com' (ED25519) to the list of known hosts.
[email protected]: Permission denied (publickey).
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.
fatal: clone of '[email protected]:maxilevi/ggml.git' into submodule path '/Users/danemadsen/vits.cpp/ggml' failed
Failed to clone 'ggml'. Retry scheduled
Cloning into '/Users/danemadsen/vits.cpp/highway'...
Cloning into '/Users/danemadsen/vits.cpp/ios-cmake'...
Cloning into '/Users/danemadsen/vits.cpp/ggml'...
[email protected]: Permission denied (publickey).
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.
fatal: clone of '[email protected]:maxilevi/ggml.git' into submodule path '/Users/danemadsen/vits.cpp/ggml' failed
Failed to clone 'ggml' a second time, aborting

[maxilevi]

Thanks!