chore(deps): update dependency @graphql-tools/schema to v9 (version-4) (#6785)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: David Glasser <glasser@apollographql.com>

Author: renovate[bot]

.changeset/spicy-pugs-deliver.md

@@ -0,0 +1,5 @@
+---
+"@apollo/server": patch
+---
+
+Update internal use of `@graphql-tools/schema` from v8 to v9. This should be a no-op; we have already removed the feature that would have been affected by the API change in this upgrade (passing `parseOptions` to `makeExecutableSchema`).