fix: upgrade gatsby from 5.0.0 to 5.12.3

Snyk has created this PR to upgrade gatsby from 5.0.0 to 5.12.3.

See this package in npm:
https://www.npmjs.com/package/gatsby

See this project in Snyk:
https://app.snyk.io/org/sammytezzy/project/f5fdc01b-8aa3-49af-9e83-74a833d59c17?utm_source=github&utm_medium=referral&page=upgrade-pr

Author: snyk-bot