Fix attempt for eigen in windows packaging

Author: julien-tierny

.github/workflows/main.yml

@@ -314,7 +314,7 @@ jobs:
       shell: bash
       run: |
         conda install -c anaconda qt boost
-        conda install -c conda-forge eigen spectralib zfp scikit-learn openmp embree3
+        conda install -c conda-forge eigen=3.3.8 spectralib zfp scikit-learn openmp embree3
 
     - name: Fetch ParaView installer
       run: |