Fix: Clone cppcheck via SSH.

Cloning cppcheck randomly failed due to the http download with the following error message:

Cloning into 'cppcheck'...
error: RPC failed; curl 92 HTTP/2 stream 0 was not closed cleanly: CANCEL (err 8)
error: 6514 bytes of body are still expected
fetch-pack: unexpected disconnect while reading sideband packet
fatal: early EOF
fatal: fetch-pack: invalid index-pack output

My hope ist, that with the increased buffer size this problem will be solved. (from here: https://docs.gitlab.com/ee/topics/git/troubleshooting_git.html)