docs(ci): replace the msstore pin's guess with the actual root cause

[mangokingTW]

The comment I added when v1.5.7's Store submit failed blamed v0.4.0's switch to NativeAOT + trimming and the Azure.Storage.Blobs 12.25.0 → 12.29.1 bump. That was wrong, and a wrong theory sitting in a pin comment is worse than no theory — the next person to touch this would have chased the build configuration.

The real cause is microsoft/msstore-cli#162:

UploadTimeoutOption = new Option<long>("--uploadTimeout", "-ut")
{
    CustomParser = result => { if (result.Tokens.Count == 0) return 100; ... }   // no DefaultValueFactory
};

System.CommandLine only invokes a CustomParser when the option is actually present on the command line. Omit it and the value falls back to default(long) = 0, which becomes Retry.NetworkTimeout = TimeSpan.FromSeconds(0) — every request is cancelled the instant it starts, the retry policy burns six attempts, and the upload fails without transferring a byte.

• Affects v0.4.0 and v0.4.1. v0.3.9 predates the option entirely.
• Presents as a bare Error while uploading the application package. after a consistent ~25s (ours was ~23s), with no stack trace. The real exception only surfaces under --verbose, which also logs the submission's SAS-bearing FileUploadUrl — so it must never run in a public CI log. That is what made it expensive to diagnose from our side.
• Fixed by #163, merged 2026-08-25. No release carries it yet — v0.4.1 shipped 2026-08-20, before the merge.

Why the pin stays at v0.3.9

v0.3.9 has neither #154 nor #162 (both were introduced in v0.4.0), and there is nothing else in v0.4.x this workflow needs. Working around #162 by passing --uploadTimeout explicitly would mean carrying someone else's bug by hand for no gain. The comment now says exactly what to wait for: a release later than v0.4.1.

Comment-only change; no behaviour difference.