Remove stray "." argument passed to `cargo run` in RustAppHostingExtension.cs

[zailic]

In src/CommunityToolkit.Aspire.Hosting.Rust/RustAppHostingExtension.cs the code invokes cargo with an extra "." argument (e.g. cargo run .). cargo run does not accept "." as a positional argument and this causes cargo to fail.

Suggested fix: Remove the stray "." so arguments become cargo run <args> or use --manifest-path if intended