fix(examples): wrong module name of nestedpkg (gnolang#2522)

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examples/gno.land/p/demo/nestedpkg/gno.mod

@@ -1,3 +1,3 @@
-module nestedpkg
+module gno.land/p/demo/nestedpkg
 
 require gno.land/r/demo/tests v0.0.0-latest