[HOTFIX] Fix syntax error in Purge CDN workflow

Author: ebronson68

.github/workflows/purge-cdn.yaml

@@ -42,23 +42,23 @@ jobs:
       - name: Purge CDN cache
         shell: pwsh
         run: |
-          if (-not ${{ inputs.cdnResourceGroup }}) {
+          if (-not "${{ inputs.cdnResourceGroup }}") {
             Write-Error "CDN Resource Group is required. Please provide the CDN Resource Group name when calling the workflow."
             exit 1
           }
           else {
             $ResourceGroup="${{ inputs.cdnResourceGroup }}"
           }
 
-          if (-not ${{ inputs.cdnProfile }}) {
+          if (-not "${{ inputs.cdnProfile }}") {
             Write-Error "CDN Profile is required. Please provide the CDN Profile name when calling the workflow."
             exit 1
           }
           else {
             $ProfileName="${{ inputs.cdnProfile }}"
           }
 
-          if (-not ${{ inputs.cdnEndpoint }}) {
+          if (-not "${{ inputs.cdnEndpoint }}") {
             if ("${{ github.event.repository.name }}" -match "*_game") {
               $EndpointName = (az afd endpoint list --profile-name "$ProfileName" --resource-group "$ResourceGroup" --query "[?tags.\"repository-name\" == '${{ github.event.repository.name }}'].name" -o tsv)
             }
@@ -71,7 +71,7 @@ jobs:
             $EndpointName="${{ inputs.cdnEndpoint }}"
           }
 
-          if (${{ inputs.resourceType }} -eq 'frontdoor') {
+          if ("${{ inputs.resourceType }}" -eq 'frontdoor') {
             Clear-AzFrontDoorEndpointContent -EndpointName $EndpointName -ProfileName $ProfileName -ResourceGroupName $ResourceGroup -ContentPaths '/*'
           }
           else {