Bump gatsby-source-filesystem from 2.8.0 to 2.8.1

Bumps [gatsby-source-filesystem](https://github.com/gatsbyjs/gatsby/tree/HEAD/packages/gatsby-source-filesystem) from 2.8.0 to 2.8.1.
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/gatsby-source-filesystem@2.8.1/packages/gatsby-source-filesystem/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/commits/gatsby-source-filesystem@2.8.1/packages/gatsby-source-filesystem)

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -77,7 +77,7 @@
     "gatsby-plugin-sharp": "^2.10.1",
     "gatsby-plugin-sitemap": "^2.9.0",
     "gatsby-plugin-svgr": "^2.0.2",
-    "gatsby-source-filesystem": "^2.8.0",
+    "gatsby-source-filesystem": "^2.8.1",
     "gatsby-transformer-sharp": "^2.9.0",
     "isomorphic-fetch": "^3.0.0",
     "moment": "^2.29.1",