Fix support for RHEL/CentOS 8

[ramereth]

RHEL 8 now ships with dnf as the primary package manager. This fix accounts for the need to use the Dnf package provider instead of the defaulted Yum provider. Without this, the converge will fail trying to use the Yum provider.

Signed-off-by: Lance Albertson lance@osuosl.org

Check List

• [ ] All tests pass. See https://github.com/chef-cookbooks/community_cookbook_documentation/blob/master/TESTING.MD
• [ ] New functionality includes testing.
• [ ] New functionality has been documented in the README if applicable
• [ ] All commits have been signed for the Developer Certificate of Origin. See https://github.com/chef-cookbooks/community_cookbook_documentation/blob/master/CONTRIBUTING.MD