Remove MD5 usage in wikicloth gem monkey patch for FIPS

What does this MR do and why?

Resolves: WikiCloth patch: Switch MD5 to SHA256 (#361266 - closed)

Removes MD5 usage in wikicloth gem monkey patch for FIPS compliance.

Screenshots or screen recordings

How to set up and validate locally

1. Create a wiki
2. Clone it
3. Create a mediawiki.mediawiki file with the following contents:

   variable: {{foo}}     
   function: {{#len:foo}}

4. Commit and push
5. Refresh the wiki and view the pushed page
6. See that it renders the same thing it previously did before this MR.
7. Also try it with a larger valid (non-variable-using) mediawiki example. E.g. the following or some other example from https://www.mediawiki.org/:

Besides Wikimedia sister projects, many other '''sites''' exist that are '''using the MediaWiki software'''. Such sites based on our software generally display the ''Powered by'' icon near the bottom right corner of their pages.

==See navigation on the right==
See navigation on the right for the collection. It is '''divided into several lists''' for the languages the wikis are written in or provided for.

==New entries==
* '''Feel free''' to add your site to the appropriate language list (select your language from the list on the right first).
* If there is no list for your language yet, add it on the [[Talk:Sites using MediaWiki|talk page]]. Entries will be sorted further. 
* New entries will be checked. Unreachable sites or sites that don't use MediaWiki will be removed.
* Please stay close to the given format:
:<code><nowiki>;Title - [https://www.example.org/ example.org] :Short description</nowiki></code>

==See also==
; Websites collecting statistics and information
* [https://wikistats.wmcloud.org/ Wikistats – a website monitoring MediaWiki wikis]
*[https://wikiapiary.com/ WikiApiary – a wiki monitoring MediaWiki wikis]
*[https://wikibase-registry.wmflabs.org/ Wikibase Registry]

; Other
* test

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.