chore(internal/gapicgen): update microgen to v0.20.1 (#4154)
chore(internal/gapicgen): update microgen to v0.20.1 (#4154)

Co-authored-by: Cody Oss <4f8e09b568d6600469c962b5159390a088c398ff@users.noreply.github.com>
googleapis/google-cloud-go,googleapis/google-cloud-go,googleapis/google-cloud-go,googleapis/google-cloud-go