fix: upgrade multiple dependencies with Snyk

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
  - gatsby-plugin-manifest from 5.0.0 to 5.12.0.
    See this package in npm: https://www.npmjs.com/package/gatsby-plugin-manifest
  - gatsby-plugin-sharp from 5.0.0 to 5.12.0.
    See this package in npm: https://www.npmjs.com/package/gatsby-plugin-sharp
  - gatsby-source-filesystem from 5.0.0 to 5.12.0.
    See this package in npm: https://www.npmjs.com/package/gatsby-source-filesystem
  - gatsby-transformer-sharp from 5.0.0 to 5.12.0.
    See this package in npm: https://www.npmjs.com/package/gatsby-transformer-sharp

See this project in Snyk:
https://app.snyk.io/org/sammytezzy/project/4f0fcef2-a8af-4f60-9617-fd0b6c05ab41?utm_source=github&utm_medium=referral&page=upgrade-pr

Author: snyk-bot