cmake: set v3.10 as minimum required version
cmake: set v3.10 as minimum required version

CMake v3.10 is available on most LTS systems (Ubuntu 18.04+,
RHEL/CentOS 8, Debian Stable, Fedora 32, FreeBSD and OpenBSD). And thus
can be tested.

Signed-off-by: GitHub <1505422b2465e9a84f6fdfaa161078890c593f06@github.com>

alanxz/rabbitmq-c,alanxz/rabbitmq-c,alanxz/rabbitmq-c