Increase minimal GCC version from 9 to 10

I want to increase Dune Core master's (will become Dune 2.10) minimal required GCC version from 9 to 10. Debian 11 comes with GCC 10. Ubuntu 20.04 provides a package gcc-10, so it is easy to use Dune with Ubuntu 22.04.

Is there any reason to not increase the minimal compiler to GCC 10?

In the Dune developer meeting 2022, we decided to increase the GCC version to 10, unless we are presented cases not considered.