[FX][EZ] Fix type correctness on GraphModule.graph (#54305)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/54305
Test Plan: Imported from OSS
Reviewed By: suo
Differential Revision: D27181176
Pulled By: jamesr66a
fbshipit-source-id: ed91cfed193984249c07a5bafc7aa732bfe0194d
