Correct a godbolt link for modules.

Author: hageboeck

talk/expert/modules.tex

@@ -116,7 +116,7 @@
       export Ratio golden() { ... } // golden is visible
     \end{cppcode*}
   \end{exampleblock}
-  \begin{exampleblockGB}{main.cpp}{https://godbolt.org/z/n95rdxPdos}{Modules example}
+  \begin{exampleblockGB}{main.cpp}{https://godbolt.org/z/G51Pq9Tbj}{Modules example}
     \begin{cppcode*}{}
       import math;
       import <iostream>;