Provide Cache-Control Headers

max-age = 1 week for everything
stale-while-revalidate = 1 day for everything except raw pastes
immutable for raw pastes

Most likely fixes #2, unless I forgot something.

Suggested-by: Leonora Tindall <ltindall@fastly.com>
Signed-off-by: Gunwant Jain <mail@wantguns.dev>

src/routes/pretty_retrieve.rs

@@ -66,7 +66,9 @@ pub async fn pretter_retrieve_inner(
     let rendered = Template::render("pretty.html", &map);
 
     match tree_magic::match_filepath("text/plain", &filepath) {
-        true => ResponseWrapper::paste_response(rendered, modified_date),
+        true => {
+            ResponseWrapper::pretty_paste_response(rendered, modified_date)
+        }
         false => ResponseWrapper::server_error("media type unacceptable"),
     }
 }