fix: upgrade multiple dependencies with Snyk

Snyk has created this PR to upgrade:
  - gatsby from 2.23.3 to 2.23.4.
    See this package in NPM: https://www.npmjs.com/package/gatsby
  - gatsby-plugin-offline from 3.2.9 to 3.2.10.
    See this package in NPM: https://www.npmjs.com/package/gatsby-plugin-offline
  - gatsby-transformer-remark from 2.8.15 to 2.8.16.
    See this package in NPM: https://www.npmjs.com/package/gatsby-transformer-remark

See this project in Snyk:
https://app.snyk.io/org/github-newrelic/project/7fcca766-b226-4202-a6f2-d2d816b1e69d?utm_source=github&utm_medium=upgrade-pr