Update ROOT dependency
While trying to compile the current version of ROOT
in use v6r20p042
by GWOLLUM
using the gcc-10.3.0
compiler, I found that does not compile successfully. To compile ROOT
successfully, I needed to use a more recent version of root (v6r26p04
https://git.ligo.org/virgo/virgoapp/root/-/merge_requests/2). This merge request updates the ROOT
used in the cmt/requirements
.