Update mermaid to 8.11.5

Mermaid before 8.11.0 allows XSS when the antiscript feature is used,
see https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-35513

Changelog: security

package.json

@@ -150,7 +150,7 @@
     "lowlight": "^1.20.0",
     "marked": "^0.3.12",
     "mathjax": "3",
-    "mermaid": "^8.10.2",
+    "mermaid": "^8.11.5",
     "minimatch": "^3.0.4",
     "monaco-editor": "^0.25.2",
     "monaco-editor-webpack-plugin": "^4.0.0",