Bump gatsby from 5.12.6 to 5.12.12

Bumps [gatsby](https://github.com/gatsbyjs/gatsby) from 5.12.6 to 5.12.12.
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/master/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/compare/gatsby@5.12.6...gatsby@5.12.12)

---
updated-dependencies:
- dependency-name: gatsby
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

package.json

@@ -23,7 +23,7 @@
     "@emotion/styled": "^11.11.0",
     "@mui/icons-material": "^5.14.13",
     "@mui/material": "^5.14.13",
-    "gatsby": "^5.12.6",
+    "gatsby": "^5.12.12",
     "html-react-parser": "^4.2.2",
     "immutability-helper": "^3.1.1",
     "katex": "^0.16.9",