internal/postgres: replace LegacyPackage in TestGetStdlibPaths

For golang/go#39629

Change-Id: Ifb6e409239decc7df7282835c9c171d033be9d33
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/262760
Trust: Julie Qiu <julie@golang.org>
Run-TryBot: Julie Qiu <julie@golang.org>
TryBot-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
diff --git a/internal/postgres/path_test.go b/internal/postgres/path_test.go
index b25f5f8..ec7e44b 100644
--- a/internal/postgres/path_test.go
+++ b/internal/postgres/path_test.go
@@ -242,7 +242,7 @@
 		},
 	} {
 		m := sample.LegacyModule(stdlib.ModulePath, data.version, data.suffixes...)
-		for _, p := range m.LegacyPackages {
+		for _, p := range m.Packages() {
 			p.Imports = nil
 		}
 		if err := testDB.InsertModule(ctx, m); err != nil {