Bump version to v0.4.0

[lukekim]

Summary

• Bump version from 0.3.0 to 0.4.0 for release

What's new in v0.4.0

• SMB connection pool — N authenticated TCP connections (default 4), round-robin dispatched (SPICEIO_SMB_CONNECTIONS)
• Pipelined reads — streaming GetObject batches 8 read requests per round trip
• TCP socket tuning — 1 MB SO_SNDBUF/SO_RCVBUF on SMB sockets
• Configurable I/O cap — SPICEIO_SMB_MAX_IO for servers supporting larger standalone read/write

Test plan

• cargo check builds at v0.4.0
• Cargo.lock updated

[Copilot]

Pull request overview

Bumps the crate version to v0.4.0 to prepare a release.

Changes:

• Update spiceio package version from 0.3.0 to 0.4.0 in Cargo.toml.
• Update the corresponding spiceio entry in Cargo.lock.

Reviewed changes

Copilot reviewed 1 out of 2 changed files in this pull request and generated no comments.

File	Description
Cargo.toml	Updates the crate’s published version to 0.4.0.
Cargo.lock	Keeps lockfile metadata consistent with the new crate version.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.