[java]: mark WebElement.getAttribute deprecated

Author: Delta456

java/src/org/openqa/selenium/WebElement.java

@@ -166,6 +166,7 @@ public interface WebElement extends SearchContext, TakesScreenshot {
    * @param name The name of the attribute.
    * @return The attribute/property's current value or null if the value is not set.
    */
+  @Deprecated
   @Nullable String getAttribute(String name);
 
   /**