Fix Python Installs about dialog

[jellespijker]

It will now use the Python Virtual env

Description

Important

Yes that weird {inner} and {outer} construct is needed due to Windows Powershell behavior

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Printer definition file(s)
• Translations

How Has This Been Tested?

• Test A
• Test B

Test Configuration:

• Operating System:

Checklist:

• My code follows the style guidelines of this project as described in UltiMaker Meta and Cura QML best practices
• I have read the Contribution guide
• I have commented my code, particularly in hard-to-understand areas
• I have uploaded any files required to test this change