fix: pass isrg cert to http client

lib/utils/custom_http_client.dart

@@ -0,0 +1,30 @@
+import 'dart:convert';
+import 'dart:io';
+
+import 'package:http/http.dart' as http;
+import 'package:http/io_client.dart';
+
+import 'package:fluffychat/config/isrg_x1.dart';
+
+class CustomHttpClient {
+  static HttpClient customHttpClient(String? cert) {
+    final context = SecurityContext.defaultContext;
+
+    try {
+      if (cert != null) {
+        final bytes = utf8.encode(cert);
+        context.setTrustedCertificatesBytes(bytes);
+      }
+    } on TlsException catch (e) {
+      if (e.osError != null &&
+          e.osError!.message.contains('CERT_ALREADY_IN_HASH_TABLE')) {
+      } else {
+        rethrow;
+      }
+    }
+
+    return HttpClient(context: context);
+  }
+
+  static http.Client createHTTPClient() => IOClient(customHttpClient(ISRG_X1));
+}