Update dependency mdsvex to ^0.12.0

Author: renovate[bot]

Experimental/website/package.json

@@ -58,7 +58,7 @@
     "github-buttons": "^2.15.0",
     "husky": "^4.3.8",
     "lint-staged": "^10.5.4",
-    "mdsvex": "^0.8.9",
+    "mdsvex": "^0.12.0",
     "netlify-lambda": "^2.0.3",
     "npm-run-all": "^4.1.5",
     "postcss": "^8.2.8",