[examples] Update remark dependency for blog-starter

[jonrosner]

Upgrade remark-html dependency to resolve the critical vulnerability.

Newer versions like 15.0.1 do not work with this example but version 13.0.2 fixes the security issue and still works.

                       === npm audit security report ===

# Run  npm install remark-html@15.0.1  to resolve 1 vulnerability
SEMVER WARNING: Recommended action is a potentially breaking change
┌───────────────┬──────────────────────────────────────────────────────────────┐
│ Critical      │ Unsafe defaults in `remark-html`                             │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ Package       │ remark-html                                                  │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ Dependency of │ remark-html                                                  │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ Path          │ remark-html                                                  │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ More info     │ https://github.com/advisories/GHSA-9q5w-79cv-947m            │
└───────────────┴──────────────────────────────────────────────────────────────┘

Bug

• Related issues linked using fixes #number
• Integration tests added
• Errors have helpful link attached, see contributing.md

Feature

• Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
• Related issues linked using fixes #number
• Integration tests added
• Documentation added
• Telemetry added. In case of a feature if it's used or not.
• Errors have helpful link attached, see contributing.md

Documentation / Examples

• Make sure the linting passes by running yarn lint

[leerob]

Thank you!