git: update to 1.8.3

No changes required, just bump the submodule and Makefile versions.

Signed-off-by: John Keeping <john@keeping.me.uk>
cgit.c: sync repo config printing with struct cgit_repo

We've now added quite a few config keys for repositories, but we've
forgotten to update the printing of it for cache files. Synchronize the
two.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>