Add support for code in blockquotes in custom renderer

[andysteadbbc]

🧐 What?

Found an error when code blocks were added in a certain way with a NOTE github action blockquote

{
    "errorType": "Error",
    "errorMessage": "Token with \"paragraph\" type was not found.\nPlease report this to https://github.com/markedjs/marked.",
    "stack": [
        "Error: Token with \"paragraph\" type was not found.",
        "Please report this to https://github.com/markedjs/marked.",
        "    at $k.parseInline (/var/task/node_modules/@bbc/morty-docs/build/index.js:476:1068)",
        "    at /var/task/node_modules/@bbc/morty-docs/build/index.js:477:230494",
        "    at Array.forEach (<anonymous>)",
        "    at Rh.blockquote (/var/task/node_modules/@bbc/morty-docs/build/index.js:477:230281)",
        "    at s.<computed> [as blockquote] (/var/task/node_modules/@bbc/morty-docs/build/index.js:476:3332)",
        "    at $k.parse (/var/task/node_modules/@bbc/morty-docs/build/index.js:475:1975)",
        "    at parse (/var/task/node_modules/@bbc/morty-docs/build/index.js:475:1296)",
        "    at tm.parse (/var/task/node_modules/@bbc/morty-docs/build/index.js:476:5638)",
        "    at Function.pt [as parse] (/var/task/node_modules/@bbc/morty-docs/build/index.js:477:239)",
        "    at dC (/var/task/node_modules/@bbc/morty-docs/build/index.js:477:230934)"
    ]
}

🛠 Fix

Add a check for this in the blcokquote custom renderer