fix(ci): stabilize oversized body check [CI]

server/tests/WebDrop.Api.Tests/ServerFixture.cs

@@ -129,10 +129,16 @@ public sealed class ServerFixture : IAsyncLifetime, IAsyncDisposable
     public async Task<HttpResponseMessage> JoinAsync(Chan ch, Who who) =>
         await Http.SendAsync(Req(HttpMethod.Post, $"/api/v1/channels/{ch.Id}/seats", who));
 
-    public async Task<HttpResponseMessage> AppendAsync(Chan ch, Who who, byte[] frame, string? maxDownloads = null)
+    public async Task<HttpResponseMessage> AppendAsync(
+        Chan ch,
+        Who who,
+        byte[] frame,
+        string? maxDownloads = null,
+        bool expectContinue = false)
     {
         var req = Req(HttpMethod.Post, $"/api/v1/channels/{ch.Id}/frames", who, Bytes(frame));
         if (maxDownloads is not null) req.Headers.Add("X-WD-Max-Downloads", maxDownloads);
+        req.Headers.ExpectContinue = expectContinue;
         return await Http.SendAsync(req);
     }