chore(test): upgrade graphql tests to use go 1.19

[mangalaman93]

GraphQL tests are failing while building images. An example CI run is here https://github.com/dgraph-io/dgraph/actions/runs/4140817871/jobs/7196716657.

Step 5/9 : RUN go get github.com/graph-gophers/graphql-go
 ---> Running in 5a79b91313d5
# github.com/graph-gophers/graphql-go/internal/exec/resolvable
Error: src/github.com/graph-gophers/graphql-go/internal/exec/resolvable/resolvable.go:96:20: undefined: reflect.Pointer
Error: src/github.com/graph-gophers/graphql-go/internal/exec/resolvable/resolvable.go:105:9: undefined: reflect.Pointer
While running command: "docker-compose --compatibility -f ../graphql/e2e/custom_logic/docker-compose.yml -p test-652-25 up --force-recreate --build --remove-orphans --detach" Error: exit status 1

[coveralls]

Coverage: 67.271% (+0.5%) from 66.818% when pulling f15610d on aman/go119 into 6a10eb9 on main.