Build failure on linux i686

Nobody has claimed this yet.

```bash
[5](https://github.com/rust-proxy/wind/actions/runs/27064116765/job/79881884126#step:13:756)
Checking tokio-quiche v0.18.0
error[E0080]: transmuting from 16-byte type to 12-byte type: `u128` -> `std::time::Instant`
Error: --> /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-quiche-0.18.0/src/quic/io/gso.rs:126:44
|
126 | const INSTANT_ZERO: Instant = unsafe { std::mem::transmute(0u128) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `quic::io::gso::send_to::{closure#0}::INSTANT_ZERO` failed here

error[E0512]: cannot transmute between types of different sizes, or dependently-sized types
Error: --> /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-quiche-0.18.0/src/quic/io/gso.rs:126:44
|
126 | const INSTANT_ZERO: Instant = unsafe { std::mem::transmute(0u128) };
| ^^^^^^^^^^^^^^^^^^^
|
= note: source type: `u128` (128 bits)
= note: target type: `std::time::Instant` (96 bits)

Some errors have detailed explanations: E0080, E0512.
For more information about an error, try `rustc --explain E0080`.
```

https://github.com/cloudflare/quiche/blob/f0c7193c3b130d766f0d6f3e75d4f2405c85d376/tokio-quiche/src/quic/io/gso.rs#L126

Issues/PR might related https://github.com/cloudflare/quiche/pull/1483

Start with tokio-quiche/src/quic/io/gso.rs at line 126 and inspect the Linux i686 failure from the linked GitHub Actions job. Compare the related cloudflare/quiche pull request 1483, then verify that the tokio-quiche check completes successfully on Linux i686 without the reported transmute errors.

Written by the indexing model from the issue text.