Add Spanish translations (419 = Latin America) (#6940)

Hi!
I have followed the instructions and added translations for Spanish,
Country Latin America 419 according to
[this](https://localizely.com/locale-code/es-419/) and other online
sources.
In the provided links there was no references to 419, but I created it
via the suggested command:
`msginit -i po/com.mitchellh.ghostty.pot -l es_419.UTF-8 -o
"po/es_419.UTF-8.po" `
Glad to be able to contribute to this excellent product!
Cheers!

src/os/i18n.zig

@@ -41,6 +41,7 @@ pub const locales = [_][:0]const u8{
     "pl_PL.UTF-8",
     "tr_TR.UTF-8",
     "id_ID.UTF-8",
+    "es_BO.UTF-8",
 };
 
 /// Set for faster membership lookup of locales.