fix test stderr

tests/testsuite/publish.rs

@@ -1737,7 +1737,7 @@ fn in_virtual_workspace() {
 
     p.cargo("publish --no-verify --token sekrit")
         .with_status(101)
-        .with_stderr("error: must use `-p` argument in virtual manifest")
+        .with_stderr("error: the `-p` argument must be specified in the root of a virtual workspace")
         .run();
 }