INSTALL.md: clone using HTTPS instead of GIT.
INSTALL.md: clone using HTTPS instead of GIT.

GitHub seems to be removing the `git://` links. Changing to `https://`
in case they are going to discontinue `git://`.

[SKIP CI]

ProgVal/Limnoria-test,ProgVal/Limnoria-test,Ban3/Limnoria,Ban3/Limnoria