style: format code with Prettier

This commit fixes the style issues introduced in a09d21f according to the output
from Prettier.

Details: None

astro.config.mjs

@@ -11,4 +11,4 @@ export default defineConfig({
             theme: syntaxTheme,
         },
     },
-})
+});

src/content/posts/markdown-cheat-sheet.md

@@ -84,9 +84,9 @@ These elements extend the basic syntax by adding additional features. Not all Ma
 
 ```json
 {
-  "firstName": "John",
-  "lastName": "Smith",
-  "age": 25
+    "firstName": "John",
+    "lastName": "Smith",
+    "age": 25
 }
 ```
 

src/styles/_header.scss

@@ -6,4 +6,4 @@
     > h1 {
         margin-bottom: calc((16px - 4px) * -1);
     }
-}
+}