Update gitleaks.yaml

Author: Edberg-Vasan

.github/workflows/gitleaks.yaml

@@ -24,6 +24,11 @@ jobs:
        uses: nuget/setup-nuget@v1
        with:
           nuget-version: latest
+     - name: Install Mono
+       if: steps.gitleaks.outcome != 'success'
+       run: |
+        sudo apt update
+        sudo apt install -y mono-complete
      - name: Install the dotnet
        if: steps.gitleaks.outcome != 'success'
        uses: actions/setup-dotnet@v3