Fix DC protest banner: Saturday, not Friday - #1120

Changed pages include:

• index.html - view
• 2023-august-nl.html - view
• 2023-july-london-13th.html - view
• 2023-july-london-18th.html - view
• 2023-july-nyc.html - view
• 2023-june-london-office-for-ai.html - view
• 2023-june-london.html - view
• 2023-june-melbourne.html - view
• 2023-may-deepmind-london.html - view
• 2023-november-uk.html - view

There are more changes not included in the list