chore: Pin Pester 5.8.0 and update PSScriptAnalyzer to 1.25.0

Pester previously floated via MinimumVersion 5.6.1, so CI installed
whatever the newest release was at bootstrap time. Pinning to 5.8.0
(current stable) makes CI deterministic. PSScriptAnalyzer moves from
1.24.0 to 1.25.0, the latest stable release (2026-03-20).

The consumer-facing minimum in PowerShellBuild.psd1 (Pester >= 5.6.1)
is intentionally unchanged; this only affects building this repo.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JHgRWPi4D2aun7CEtwLz7T

Author: tablackburn

instructions/repository-specific.instructions.md

@@ -225,9 +225,9 @@ Defined in `requirements.psd1`, installed via **PSDepend** when `./build.ps1 -Bo
 | Module           | Version  |
 | ---------------- | -------- |
 | BuildHelpers     | 2.0.16   |
-| Pester           | ≥ 5.6.1  |
+| Pester           | 5.8.0    |
 | psake            | 4.9.0    |
-| PSScriptAnalyzer | 1.24.0   |
+| PSScriptAnalyzer | 1.25.0   |
 | InvokeBuild      | 5.8.1    |
 | platyPS          | 0.14.2   |
 

requirements.psd1

@@ -4,13 +4,13 @@
     }
     BuildHelpers     = '2.0.16'
     Pester           = @{
-        MinimumVersion = '5.6.1'
-        Parameters     = @{
+        Version    = '5.8.0'
+        Parameters = @{
             SkipPublisherCheck = $true
         }
     }
     psake            = '4.9.0'
-    PSScriptAnalyzer = '1.24.0'
+    PSScriptAnalyzer = '1.25.0'
     InvokeBuild      = '5.8.1'
     platyPS          = '0.14.2'
 }