build(deps): bump gatsby-source-filesystem in /docs (#1389)

Bumps [gatsby-source-filesystem](https://github.com/gatsbyjs/gatsby/tree/HEAD/packages/gatsby-source-filesystem) from 2.3.29 to 2.3.30.
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/master/packages/gatsby-source-filesystem/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/commits/[email protected]/packages/gatsby-source-filesystem)

Signed-off-by: dependabot[bot] <[email protected]>
Signed-off-by: Xiang Dai <[email protected]>
Co-authored-by: Xiang Dai <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

docs/package-lock.json

@@ -34,7 +34,7 @@
     "gatsby-remark-images": "^3.3.29",
     "gatsby-remark-mermaid": "^2.1.0",
     "gatsby-remark-responsive-iframe": "^2.4.12",
-    "gatsby-source-filesystem": "^2.3.29",
+    "gatsby-source-filesystem": "^2.3.30",
     "gatsby-transformer-remark": "^2.8.28",
     "gatsby-transformer-sharp": "^2.5.13",
     "gatsby-transformer-yaml": "^2.4.11",