fix: update shell type from pwsh to powershell in deployment workflow

Author: frasermolyneux

.github/workflows/deploy-prd.yml

@@ -26,7 +26,7 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: Run certificate rotation
-        shell: pwsh
+        shell: powershell
         run: |
           Write-Host "Running on $($env:COMPUTERNAME)"
           .\rotate-iis-certificates.ps1 -cloudflareApiKey "${{ secrets.CLOUDFLARE_API_KEY }}"