Fix Windows: use 'powershell' instead of 'pwsh'

PowerShell Core (pwsh) is not installed on the Windows runner.
Windows PowerShell 5.1 (powershell) is always available.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.gitea/workflows/release.yml

@@ -131,7 +131,7 @@ jobs:
           echo Definitions and docs packaged
 
       - name: Update Package Versions
-        shell: pwsh
+        shell: powershell
         run: |
           $VERSION = $env:CLEAN_VERSION
           $CHANNEL = $env:CHANNEL