Add more verbose logging when tauri fails to parse a Cargo.toml in a parent workspace

[edgex004]

Is your feature request related to a problem? Please describe.
Split from #2508. I had to pull the tauri source and debug re.cli in order to determine why my build was failing. If there logging was a bit more verbose, the problem with my project files might have been made clear without ever touching the rs.cli code.

Error currently looks like:

Error: failed to rename `/Users/edgex004/Code/test-tauri-app/src-tauri/target/release/app` to `/Users/edgex004/Code/test-tauri-app/src-tauri/target/release/test-tauri-app`

Caused by:
    No such file or directory (os error 2)

Describe the solution you'd like
Adding a warning printout to cli.rs for when get_workspace_dir finds a Cargo.toml in a parent directory, but fails to parse it for some reason. Print the parser error context here.

I have done this on a branch. Error now looks like:

[tauri:build] Found `/Users/edgex004/Code/test-tauri-app`, which may define a parent workspace, but failed to parse it. If this is indeed a parent workspace, undefined behavior may occur: 
    failed to parse Cargo.toml: missing field `description` for key `package` at line 18 column 1
Error: failed to rename `/Users/edgex004/Code/test-tauri-app/src-tauri/target/release/app` to `/Users/edgex004/Code/test-tauri-app/src-tauri/target/release/test-tauri-app`

Caused by:
    No such file or directory (os error 2)

Describe alternatives you've considered
Alternatives I thought of are:

• to error out in this case instead.
• make the Cargo.toml parser more lax.

Additional context
None

[edgex004]

My suggested fix is here.

It is probably not the best solution, but perhaps it can give someone else a better idea.