chore: update to serene v5.5.0

The figure shortcode no longer has a `via` attribute. Instead, the `caption` attribute now supports Markdown, so you can pass a link like `[via](...)`. This makes the shortcode override obsolute, so I deleted it.

Author: BD103

content/blog/2023-08-06-ptr-metadata.md

@@ -167,4 +167,4 @@ If you have any questions, feel free to comment on [my post](https://users.rust-
 
 Cheers!
 
-{{ figure(src = "https://www.rustacean.net/assets/rustacean-flat-happy.svg", alt = "Ferris the crab, Rust's unofficial mascot, smiling", caption = "Ferris the happy crab", via = "https://rustacean.net/", width = "200rem") }}
+{{ figure(src = "https://www.rustacean.net/assets/rustacean-flat-happy.svg", alt = "Ferris the crab, Rust's unofficial mascot, smiling", caption = "Ferris the happy crab", caption = "[via](https://rustacean.net/)", width = "200rem") }}

content/blog/2025-09-09-bevys-5th-birthday.md

@@ -28,7 +28,7 @@ Now the idea of a Bevy CLI has been around for quite some time, with [an issue o
 
 So...
 
-{{ figure(src = "/img/2025-09-09-bevys-5th-birthday/nerd-sniping.png", alt = "A comic panel of a truck running someone over", caption = "I was thoroughly nerd-sniped", via = "https://xkcd.com/356/") }}
+{{ figure(src = "/img/2025-09-09-bevys-5th-birthday/nerd-sniping.png", alt = "A comic panel of a truck running someone over", caption = "I was thoroughly nerd-sniped, [via](https://xkcd.com/356/)") }}
 
 ## Thankfully I Did Not Get Run Over by a Truck[^1]