fix: preview deploy for PRs (#990)

Co-authored-by: kolaente <k@knt.li>
Reviewed-on: https://kolaente.dev/vikunja/frontend/pulls/990
Co-authored-by: konrad <k@knt.li>
Co-committed-by: konrad <k@knt.li>

netlify.toml

@@ -1,3 +1,15 @@
 [build]
   command = "yarn build"
   publish = "dist"
+
+[[redirects]]
+  from = "/*"
+  to = "/index.html"
+  status = 200
+
+[[headers]]
+  for = "/*"
+  [headers.values]
+  	X-Frame-Options = "DENY"
+	X-XSS-Protection = "1; mode=block"
+	X-Robots-Tag = "noindex"