Please Move your **lightning:progressIndicator ** inside div tag as below,

<div class="slds-readonly-path">


 <lightning:progressIndicator aura:id="progress" currentStep="{!v.Stage}"
      type="path"/> 

   
    </div>
enter code here

CSS:

.THIS.slds-readonly-path{
pointer-events: none;

}

Please Move your lightning:progressIndicator inside div tag as below,

<div class="slds-readonly-path">

    <lightning:progressIndicator aura:id="progress"
          currentStep="{!v.Stage}" type="path"/> 
       
</div>

CSS:

.THIS.slds-readonly-path{
    pointer-events: none;
}