chore: Dumb prealloc lint fix (#7430)

modules/caddyhttp/server.go

@@ -1010,6 +1010,7 @@ func isTrustedClientIP(ipAddr netip.Addr, trusted []netip.Prefix) bool {
 // then the first value from those headers is used.
 func trustedRealClientIP(r *http.Request, headers []string, clientIP string) string {
 	// Read all the values of the configured client IP headers, in order
+	// nolint:prealloc
 	var values []string
 	for _, field := range headers {
 		values = append(values, r.Header.Values(field)...)