ci: fix post clone and test step (#2845)

Author: ansys-akarcher

.github/workflows/pydpf-post.yml

@@ -65,6 +65,7 @@ jobs:
         run: |
           echo "ANSYS_DPF_ACCEPT_LA=Y" >> $GITHUB_ENV
           echo "ANSYSLMD_LICENSE_FILE=1055@${{ secrets.LICENSE_SERVER }}" >> $GITHUB_ENV
+          echo "DPF_DEFAULT_GRPC_MODE=insecure" >> $GITHUB_ENV
 
       - name: "Setup Python"
         uses: actions/setup-python@v5