passing single-digit version fails

```
PS> .\PythonEmbed4Win.ps1  -Verbose -Version 3
PythonEmbed4Win.ps1: at <ScriptBlock>, PythonEmbed4Win.ps1: line 1150
at <ScriptBlock>, <No file>: line 1
PythonEmbed4Win.ps1: Cannot convert value "3" to type "System.Version". Error: "Version string portion was too short or too long. (Parameter 'input')
```

Though it's a bit silly to pass `-Version 3`, it shouldn't crash like this.