Upgrade to PowerShell 7

[JunielKatarn]

Description

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Why

PowerShell 7 offers multiple performance improvements over Windows PowerShell (5.1).

🔍 PowerShell 7.x vs Windows PowerShell 5.1 — Performance & Security

Dimension	Windows PowerShell 5.1	PowerShell 7.x (incl. 7.6 LTS)
Runtime	.NET Framework 4.x 【1-9d0dcf】	Modern .NET (Core → .NET 8/9/10) 【1-9d0dcf】
Performance (overall)	Baseline performance	~2–3× faster for common operations (arrays, strings, module load) 【2-7415bb】
Parallel execution	No native pipeline parallelism	Native parallelism (ForEach-Object -Parallel) 【3-bc07e3】
Memory efficiency	Less efficient (older runtime)	Improved memory management and efficiency 【2-7415bb】
Module loading	Slower	Faster module loading 【2-7415bb】
Optimization level	Limited (legacy runtime)	Continuously optimized via modern .NET 【1-9d0dcf】
Security model (lifecycle)	Maintenance mode (security fixes only) 【3-bc07e3】	Actively developed with ongoing improvements 【3-bc07e3】
Platform security baseline	Older .NET + Windows-only stack	Modern .NET with updated crypto, TLS, runtime security 【1-9d0dcf】
Update model	Tied to Windows updates	Independent updates (faster patching) 【4-202161】
Execution policy	Independent config (often Restricted by default) 【5-d94a22】	Independent config (often RemoteSigned by default) 【5-d94a22】
Attack surface	Includes legacy Windows-specific components	Reduced legacy surface, more modern APIs 【3-bc07e3】

See https://techieramesh.com/devops/windows-automation/ps-5-1-vs-7-5-comparison/

What

• Ensure PowerShell 7 is installed (NuGet package to reduce set up footprint on the developer's machine).
• Replace all references to powershell.exe with pwsh.exe.

Testing

CI checks pass

Microsoft Reviewers: Open in CodeFlow