[MOLECULE 3.3.0] Upgrade linters Molecule setup

In 3.x.x version family of Molecule the syntax for linters
invocation has been changed.

Ref.: https://molecule.readthedocs.io/en/latest/configuration.html#lint

Change-Id: I82d1fd996eb5853953ea6bc74dcbb88a485a2084
Issue-ID: OOM-2722
Signed-off-by: Bartek Grzybowski <b.grzybowski@partner.samsung.com>
diff --git a/ansible/roles/nexus/.yamllint b/ansible/roles/nexus/.yamllint
index ad0be76..c5ae64b 100644
--- a/ansible/roles/nexus/.yamllint
+++ b/ansible/roles/nexus/.yamllint
@@ -1,3 +1,4 @@
+---
 extends: default
 
 rules: