Update gomplate to 5.0.0

The release of gomplate 5.0.0 is imminent (see the issue, the maintainer pushed a release and it is currently testing/building in CI/CD as of today 2026-01-13) so putting this on radar to update ASAP.

gomplate 4.3.2 as currently used by CNG has a number of vulnerabilities in the libraries it uses that are only fully addressed with 5.0.0.

CVEs resolved by updating to 5.0.0 include: