403 error when proposing changes to docs via stackblitz

[rynop]

Repro:

1. From https://docs.nativescript.org/project-structure/src/fonts click on "Edit this page" (brings you to https://stackblitz.com/~/github.com/NativeScript/docs/edit/main/content/project-structure/src/fonts.md?initialPath=%2Fproject-structure%2Fsrc%2Ffonts)
2. Edit doc. Ex: I'm trying to add this section (remove the leading \ on codeblock)

::: warning Note Material icons users
Material icons uses [Ligatures](https://developer.mozilla.org/en-US/docs/Glossary/Ligature) instead of char codes. 

\```xml
<Label class="mat-icon-filled" text="person" />
\```
:::

3. Hit "Propose changes" button, then "Fork & Commit changes"
4. View error in browser console: