chore(localhost): disable caching (#3112)

* chore(localhost): disable caching

mostly seeing this cache being a problem on CEF - the response is cached so app updates are not reflected properly

* fmt

.changes/disable-localhost-plugin-caching.md

@@ -0,0 +1,5 @@
+---
+"localhost": patch
+---
+
+Disable caching on responses.

plugins/localhost/src/lib.rs

@@ -105,6 +105,10 @@ impl Builder {
                                     .insert("Content-Security-Policy".into(), csp);
                             }
 
+                            response
+                                .headers
+                                .insert("Cache-Control".into(), "no-cache".into());
+
                             if let Some(on_request) = &on_request {
                                 on_request(&request, &mut response);
                             }