fix: small locator fix for by tag in page element (#3530)

due to the missing . character in the xpath, it was not possible to locate nested elements by tag, as the elements were being searched for in document root rather than current node. The applied fix resolves this issue.

serenity-screenplay-webdriver/src/main/java/net/serenitybdd/screenplay/ui/PageElement.java

@@ -13,7 +13,7 @@
 public class PageElement {
 
     private static final String BY_NAME_ID_OR_ARIA_LABEL = "css:[id='{0}' i],[name='{0}' i],[data-test='{0}' i],[aria-label='{0}' i]";
-    private static final String BY_TAG = "xpath://{0}";
+    private static final String BY_TAG = "xpath:.//{0}";
 
     /**
      * Locate an element with a given name.