ci: replace all pwsh with powershell for gitea-act runner compatibility

.gitea/workflows/ci.yml

@@ -92,7 +92,7 @@ jobs:
           Write-Host "NuGet cache hit: ${{ steps.nuget-cache.outputs.cache-hit }}"
 
       - name: Run tests (if any test projects exist)
-        shell: pwsh
+        shell: powershell
         run: |
           $ErrorActionPreference = "Stop"
           $tests = @(Get-ChildItem -Recurse -Filter "*Tests.csproj" | Where-Object { $_.FullName -notlike "*\obj\*" -and $_.FullName -notlike "*\bin\*" })
@@ -148,7 +148,7 @@ jobs:
         run: dotnet tool restore
 
       - name: Package with Velopack (Setup.exe + Portable.zip)
-        shell: pwsh
+        shell: powershell
         run: |
           $ErrorActionPreference = "Stop"
           & powershell.exe -NoProfile -ExecutionPolicy Bypass -File scripts/release/package-velopack.ps1