fix: do not handle requests to Mercure as PHP routes (#696)

Co-authored-by: Kévin Dunglas <kevin@dunglas.fr>

frankenphp/Caddyfile

@@ -44,9 +44,14 @@
 	# Disable Topics tracking if not enabled explicitly: https://github.com/jkarlin/topics
 	header ?Permissions-Policy "browsing-topics=()"
 
-	@phpRoute not file {path}
+	@phpRoute {
+		not path /.well-known/mercure*
+		not file {path}
+	}
 	rewrite @phpRoute index.php
+
 	@frontController path index.php
 	php @frontController
+
 	file_server
 }