Fix MSIHANDLE parameter modification in Rust 1.78.0+

[ZachNo]

Rust 1.78.0 seems to have changed the behavior of passing references into FFI functions so that mut is required for it to be mutable. (I assume as it should have always done)

I was running into issues with the open_view command returning a null MSIHANDLE, when the MSI log shows that it should returning the newly created MSI handle from the OpenView call.

Changing the function signature to include mut makes my previously working pre-1.78.0 custom action work again in 1.78.0

Ran cargo test --all-features and all passed.

[heaths]

Looks great, thanks! Yeah, they probably should've been mut in the first place. It crossed my mind, but since it worked without and didn't require everyone to declare mut locals I figured, "Why make em' jump through hoops unnecessarily." The answer was "future proofing" 😄!

[heaths]

Do you need a new build anytime soon? I've been working on a few minor changes for better testing but haven't had much time. If you need something sooner, I can get a point release out.

[ZachNo]

Thanks! I'm personally not in a huge rush, but an updated release may help anyone else scratching their head as to why the package doesn't appear to work in some cases with the newest Rust versions c:

[heaths]

I went ahead and released https://github.com/heaths/msica-rs/releases/tag/v0.4.1