fix(certificates): ensure `openssl` installed before `cmd.run`

Fix failure highlighted on OpenSUSE Tumbleweed, where the `cmd.run` runs
before the `pkg.installed`:

* https://gitlab.com/saltstack-formulas/nginx-formula/-/jobs/1345325819#L2830

nginx/certificates.sls

     - creates: {{ certificates_path }}/{{ dh_param }}
     - require:
       - file: prepare_certificates_path_dir
+      - pkg: generate_nginx_dhparam_{{ dh_param }}_key
     - watch_in:
       - service: nginx_service
 {%- endif %}