build: remove github.com/vektah/gqlparser

[kzys]

While we are not affected by the CVE, we don't use the package anymore.

https://github.com/advisories/GHSA-2hmf-46v7-v6fx

Change Summary

What and Why:

How:

Related to:

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Documentation

• [ ] Fresh Produce
• [ ] In superfly/docs, or asked for help from docs team
• [x] n/a