UI: Set accessible name for adv audio props button

People who are blind cannot know what the button does due to lack of any
strings associated with the button.

obs/forms/OBSBasic.ui

@@ -334,7 +334,7 @@
                </property>
                <property name="defaultDropAction">
                 <enum>Qt::TargetMoveAction</enum>
-	       </property>
+               </property>
                <addaction name="actionRemoveScene"/>
               </widget>
              </item>
@@ -416,6 +416,9 @@
               <height>22</height>
              </size>
             </property>
+            <property name="accessibleName">
+             <string>Basic.AdvAudio</string>
+            </property>
             <property name="text">
              <string notr="true"/>
             </property>
@@ -521,7 +524,7 @@
                </property>
                <property name="selectionMode">
                 <enum>QAbstractItemView::ExtendedSelection</enum>
-	       </property>
+               </property>
                <addaction name="actionRemoveSource"/>
               </widget>
              </item>