`dotnet completions script nushell` generates and invalid script

### Describe the bug
Running `dotnet completions script nushell` generates an invalid Nushell script.

### To Reproduce
Run `dotnet completions script nushell | save -f vendor/autoload/dotnet.nu`
Then open a new Nushell terminal

### Exceptions (if any)
```
Error: nu::parser::assignment_requires_variable

× Assignment operations require a variable.
╭─[/Users/my_user/Library/Application Support/nushell/vendor/autoload/dotnet.nu:16:1]
15 │
16 │ let-env config = {
· ───────┬──────
· ╰── needs to be a variable
17 │ # your options here
╰────
help: try assigning to a variable or a cell path of a variable
```

### Further technical details
It appears the command you are using was removed years ago
https://github.com/nushell/nushell/discussions/11816
https://github.com/nushell/nushell/issues/8890

details of dotnet --info

.NET SDK:
Version: 10.0.102
Commit: 4452502459
Workload version: 10.0.100-manifests.73000c7b
MSBuild version: 18.0.7+445250245

Runtime Environment:
OS Name: Mac OS X
OS Version: 15.7
OS Platform: Darwin
RID: osx-arm64
Base Path: /usr/local/share/dotnet/sdk/10.0.102/

.NET workloads installed:
There are no installed workloads to display.
Configured to use workload sets when installing new manifests.
No workload sets are installed. Run "dotnet workload restore" to install a workload set.

Host:
Version: 10.0.2
Architecture: arm64
Commit: 4452502459

.NET SDKs installed:
6.0.424 [/usr/local/share/dotnet/sdk]
8.0.303 [/usr/local/share/dotnet/sdk]
9.0.101 [/usr/local/share/dotnet/sdk]
10.0.102 [/usr/local/share/dotnet/sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 6.0.32 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 8.0.7 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 9.0.0 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 10.0.2 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 6.0.32 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 8.0.7 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 9.0.0 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 10.0.2 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

Other architectures found:
None

Environment variables:
Not set

global.json file:
Not found

Learn more:
https://aka.ms/dotnet/info

Download .NET:
https://aka.ms/dotnet/download

- The IDE (VS / VS Code/ VS4Mac) you're running on, and its version