Bump gatsby-source-filesystem from 2.3.19 to 2.3.20

Bumps [gatsby-source-filesystem](https://github.com/gatsbyjs/gatsby/tree/HEAD/packages/gatsby-source-filesystem) from 2.3.19 to 2.3.20.
- [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/gatsby-source-filesystem@2.3.20/packages/gatsby-source-filesystem)

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

package.json

@@ -16,7 +16,7 @@
     "gatsby-plugin-robots-txt": "^1.5.1",
     "gatsby-plugin-sass": "^2.3.12",
     "gatsby-plugin-sharp": "^2.6.20",
-    "gatsby-source-filesystem": "^2.3.19",
+    "gatsby-source-filesystem": "^2.3.20",
     "gatsby-transformer-sharp": "^2.5.11",
     "http-status-codes": "^1.4.0",
     "jsonp": "^0.2.1",

yarn.lock

@@ -6574,10 +6574,10 @@ gatsby-recipes@^0.1.53:
     ws "^7.3.0"
     xstate "^4.11.0"
 
-gatsby-source-filesystem@^2.3.19:
-  version "2.3.19"
-  resolved "https://registry.yarnpkg.com/gatsby-source-filesystem/-/gatsby-source-filesystem-2.3.19.tgz#48871ca06d1dc431f415f72476f9358a59e6910c"
-  integrity sha512-vFNm1Qx7nHJVtnvA1tsQYNYdr7co8hI8rrt7OwIExW19ouryqSNtzSs7T2MHQNyeXLuIajEA2xOh4Q1OgC+9UA==
+gatsby-source-filesystem@^2.3.20:
+  version "2.3.20"
+  resolved "https://registry.yarnpkg.com/gatsby-source-filesystem/-/gatsby-source-filesystem-2.3.20.tgz#fefd30acf0c4297e401570d78d9a0b073188ded1"
+  integrity sha512-zwHsOe3BipnGeHvCNz4JSzz9bWbQEFgbpkjCpmOSsPtbNaKKbk7bK8TCLGj268K24x7E5fGuXPTLqXcRfYgEOA==
   dependencies:
     "@babel/runtime" "^7.10.3"
     better-queue "^3.8.10"