buildman: Update to grabbing gcc-14.2.0 toolchains by default

With the switch to using GCC 14.2.0 in commit 001bac5f16ad ("Dockerfile:
Update to gcc-14.2.0 and clang-18") in CI, we should make buildman match
this.

Signed-off-by: Tom Rini <trini@konsulko.com>
1 file changed