Auto-update Windows DF version to 50.15 in symbols

Author: github-actions[bot]

symbols.xml

@@ -123,7 +123,7 @@
         <binary-timestamp value='0x00000000'/>
     </symbol-table>
 
-    <symbol-table name='v0.50.0 win64 STEAM' os-type='windows'>
+    <symbol-table name='v0.50.15 win64 STEAM' os-type='windows'>
         <binary-timestamp value='0x6759D35D'/>
 
         <global-address name='texture' value='0x1422308d0'/>