explicitly install cronie on EL8+

[evgeni]

cronie is a weak dependency of crontabs, and while CentOS and RHEL install weak dependencies by default, other EL systems do not (so much for compatibility, huh?).

install cronie explicitly, to avoid "Could not find a suitable provider for cron" errors on those EL systems.

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (1528466) 0.72% compared to head (1201030) 0.72%.

❗ Current head 1201030 differs from pull request most recent head cbc145b. Consider uploading reports for the commit cbc145b to get more accurate results

Additional details and impacted files

@@          Coverage Diff           @@
##           master    #343   +/-   ##
======================================
  Coverage    0.72%   0.72%           
======================================
  Files          15      15           
  Lines        1801    1801           
======================================
  Hits           13      13           
  Misses       1788    1788           

Files	Coverage Δ
lib/beaker-hostgenerator/hypervisor/docker.rb	0.00% <0.00%> (ø)

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