pandoc: apply patch removing the usage of polyfill.io in the templates
If you output HTML with MathJax content Pandoc might uses a JS library
provided by cdn.polyfill.io which is now considered to be a bad actor.
https://sansec.io/research/polyfill-supply-chain-attack
`haskellPackages.pandoc` is not impacted, the concerned domain is not used
To reproduce the issue:
1. Create a file `math.tex` with the following content `$a^2 + b^2 = c^2$`
2. Call `pandoc` with `pandoc math.tex -s --mathjax -o ex.html`
3. Look at the injected scripts in `ex.html`