Issue title: greeter/api/graphql example cannot be compiled
 Issue body: The compile error output is :
`graphql/generated.go:236:3: unknown field 'IsMethod' in struct literal of type graphql.ResolverContext
graphql/generated.go:263:3: unknown field 'IsMethod' in struct literal of type graphql.ResolverContext
graphql/generated.go:294:3: unknown field 'IsMethod' in struct literal of type graphql.ResolverContext
graphql/generated.go:325:3: unknown field 'IsMethod' in struct literal of type graphql.ResolverContext
graphql/generated.go:349:3: unknown field 'IsMethod' in struct literal of type graphql.ResolverContext
graphql/generated.go:376:3: unknown field 'IsMethod' in struct literal of type graphql.ResolverContext
graphql/generated.go:400:3: unknown field 'IsMethod' in struct literal of type graphql.ResolverContext
graphql/generated.go:427:3: unknown field 'IsMethod' in struct literal of type graphql.ResolverContext
graphql/generated.go:454:3: unknown field 'IsMethod' in struct literal of type graphql.ResolverContext
graphql/generated.go:481:3: unknown field 'IsMethod' in struct literal of type graphql.ResolverContext
graphql/generated.go:481:3: too many errors
`

The reason is gqlgen version in go.mod is v0.7.1, which doesn't contain member IsMethod in struct ResolverContext. The fix method is changing the version to v0.8.3.
 Comments: 
 Comment 0: Updated. I believe this should be fixed.
{'source': 'GithubIssues', 'repo_name_with_owner': 'micro/examples', 'issue_id': 438132980, 'repo_stars': 1161.0}