chore: remove mermaid.js

We're not using mermaid for diagrams anymore so we can prune the
dependency.

Signed-off-by: David Karlsson <35727626+dvdksn@users.noreply.github.com>

package.json

@@ -21,7 +21,6 @@
     "@tailwindcss/typography": "^0.5.8",
     "alpinejs": "^3.12.3",
     "autoprefixer": "^10.4.14",
-    "mermaid": "^10.3.1",
     "postcss": "^8.4.19",
     "postcss-cli": "^10.1.0",
     "postcss-import": "^15.1.0",