Fix the legacy posts imported in Zola

[thibaultamartin]

Todo once #1511 #1512 #1513 #1514 #1515 #1516 #1517 #1518 and #1519 have been merged:

• [ ] Replace all <code> blocks in the markdown by actual code blocks
• [ ] Replace all <pre> blocks by actual code blocks
• [ ] Replace all <a> links by []() links
• [ ] Download "legacy" images, add them next to the post markdown, and replace <img> tags by ![]()
• [ ] Replace all <ul>/<ol> <li> by -
• [x] Remove  
• [x] Replace & with &
• [x] Replace <hX> by X*# (from h1 to h5)
• [ ] Remove <p> tags
• [ ] Replace [embed] with https://regex101.com/r/nQOzcm/1
• [ ] Replace [caption]s with something
• [ ] Replace <b> and <strong> tags with **this is bold**
• [ ] Replace <i> and <em> tags with *this is italics*
• [ ] Remove <div> (let's check none is super important first)
• [ ] Remove <dl> <dt> <dd> tags
• [ ] Remove non-standard tags (<tt>??)
• [ ] Make sure we have no h1 or # level-one headings within posts
• [ ] Crawl media and make sure none is broken
• [ ] When youtube players are embedded, at least make sure loading="lazy" exists
• [x] Replace <blockquote> with >
• [ ] Replace <hr /> with ---
• [ ] Remove <br /> or replace with \ at the end of the line
• [ ] List all markdown files with <script> tags and check what they do?
• [x] Replace <del> with ~~? Depending on the markdown flavour we support
• [ ] List all markdown files with <div> tags and check what they do?
• [ ] Update the YouTube embeds so they lazy load and have a decent size by default?
• [x] Remove empty class="anchor" links
• [ ] Add <!-- more --> cutoff points for summary generation (to make the blog article listings easier to skim)

[vedant-z]

@thibaultamartin May I work on any issue in this, like removing all <p> tags ?

[thibaultamartin]

Hi vedant-z, feel free to give it a go and open a PR against the zola branch when you're ready :)

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