Fixed mt.exe check for installer script

.forgejo/workflows/Installer_Windows-AMD64-Nightly.yaml

@@ -28,7 +28,12 @@ jobs:
       - name: Check mt.exe availability
         shell: bash
         run: |
-          mt.exe /? > /dev/null 2>&1 || { echo "mt.exe not available, please install the Windows SDK"; exit 1; }
+          if ! command -v mt.exe > /dev/null 2>&1; then
+            echo "mt.exe not available, please install the Windows SDK"
+            exit 1
+          else
+            echo "mt.exe is available"
+          fi
 
       - name: Clone Publisher repo and Generate Manifest Files
         shell: bash