Template option --powershell-standard-version incorrectly lists 5.1.0 instead of its current choice of 7.0.0-preview.1

# To reproduce:
```powershell
dotnet new -i ./src/dotnetTemplate/Microsoft.PowerShell.Standard.Module.Template/Microsoft.PowerShell.Standard.Module.Template
dotnet new psmodule --help
```

# Actual output contains:
```text
  -v|--powershell-standard-version
                                        5.1.0               - PowerShell Standard 5.1
                                        3.0.0-preview-02    - PowerShell Standard 3.0
```

# Expected (according to `README.md`):
```text
  -v|--powershell-standard-version
                                        7.0.0-preview.1     - PowerShell Standard 7.0.0-preview.1
                                        3.0.0-preview-02    - PowerShell Standard 3.0
                                    Default: 7.0.0-preview.1
```


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Template option --powershell-standard-version incorrectly lists 5.1.0 instead of its current choice of 7.0.0-preview.1 #87

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Actual output contains:

Expected (according to `README.md`):

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Template option --powershell-standard-version incorrectly lists 5.1.0 instead of its current choice of 7.0.0-preview.1 #87

Description

To reproduce:

Actual output contains:

Expected (according to README.md):

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions

Expected (according to `README.md`):