RHDEVDOCS 6357 change Pipelines version attributes in OCP docs to 1.18

Author: mramendi

_attributes/common-attributes.adoc

@@ -94,8 +94,8 @@ endif::[]
 //pipelines
 :pipelines-title: Red Hat OpenShift Pipelines
 :pipelines-shortname: OpenShift Pipelines
-:pipelines-ver: pipelines-1.17
-:pipelines-version-number: 1.17
+:pipelines-ver: pipelines-1.18
+:pipelines-version-number: 1.18
 :tekton-chains: Tekton Chains
 :tekton-hub: Tekton Hub
 :artifact-hub: Artifact Hub