Switch to mpi4py/setup-mpi for MPI setup in Windows builds

Replaced manual MPICH installation and configuration with `mpi4py/setup-mpi` GitHub action for streamlined MPI setup. Updated CMake configuration to require MPI and removed redundant MPICH-specific setup steps.

Author: allnes

.github/workflows/main.yml

@@ -843,16 +843,10 @@ jobs:
         with:
           version: "17.0"
 
-      - name: Download MPICH (64-bit)
-        run: |
-          curl -LO https://www.mpich.org/static/downloads/4.2/mpich-4.2-windows-x86_64.zip
-          unzip mpich-4.2-windows-x86_64.zip -d mpich
-          echo "MPICH installed"
-
-      - name: Setup environment for MPICH
-        run: |
-          echo "$GITHUB_WORKSPACE/mpich/bin" >> $GITHUB_PATH
-          echo "MPICH_ROOT=$GITHUB_WORKSPACE/mpich" >> $GITHUB_ENV
+      - name: Setup MPI
+        uses: mpi4py/setup-mpi@v1
+        with:
+          mpi: msmpi
 
       - name: Setup ccache
         uses: Chocobo1/setup-ccache-action@v1

modules/core/CMakeLists.txt

@@ -54,6 +54,7 @@ if(NOT MSVC)
   endif()
 endif()
 
+find_package(MPI REQUIRED)
 if( MPI_COMPILE_FLAGS )
   set_target_properties(${exec_func_lib} PROPERTIES COMPILE_FLAGS "${MPI_COMPILE_FLAGS}")
 endif( MPI_COMPILE_FLAGS )