fix(seo): emit literal \\u003c in JSON-LD, not a raw less-than

In JS source "\u003c" is the character "<", so the prior replace was a
no-op. Use "\\u003c" so the serialized payload contains the six-character
escape sequence and cannot close the script element early.

Signed-off-by: Sebastien Tardif <sebtardif@ncf.ca>

Author: SebTardif

src/layouts/Layout.astro

@@ -76,7 +76,7 @@ const structuredDataItems = structuredData ? Array.isArray(structuredData) ? str
     <title>{title}</title>
 
     {structuredDataItems.map((item) => (
-      <script type="application/ld+json" set:html={JSON.stringify(item).replace(/</g, "\u003c")} />
+      <script type="application/ld+json" set:html={JSON.stringify(item).replace(/</g, "\\u003c")} />
     ))}
 
     <script is:inline>