ci(post): fix platform detection in pydpf-post test pipeline (#2811)

Author: PProfizi

.github/workflows/pydpf-post.yml

@@ -77,7 +77,7 @@ jobs:
       - name: "Build ansys-dpf-core wheel"
         shell: bash
         run: |
-          if [ ${{ matrix.os }} == "ubuntu-latest" ]; then
+          if [[ ${{ matrix.os }} == *"ubuntu"* ]]; then
               export platform="manylinux_2_17"
           else
               export platform="win"