cmake: make ortools install in venv more robuste (#3260)

cmake/python.cmake

@@ -376,7 +376,8 @@ if(BUILD_TESTING)
     #COMMAND ${VENV_EXECUTABLE} ${VENV_DIR}
     # Must NOT call it in a folder containing the setup.py otherwise pip call it
     # (i.e. "python setup.py bdist") while we want to consume the wheel package
-    COMMAND ${VENV_Python3_EXECUTABLE} -m pip install --find-links=${CMAKE_CURRENT_BINARY_DIR}/python/dist ${PYTHON_PROJECT}
+    COMMAND ${VENV_Python3_EXECUTABLE} -m pip install
+      --find-links=${CMAKE_CURRENT_BINARY_DIR}/python/dist ${PYTHON_PROJECT}==${PROJECT_VERSION}
     # install modules only required to run examples
     COMMAND ${VENV_Python3_EXECUTABLE} -m pip install pandas matplotlib pytest
     BYPRODUCTS ${VENV_DIR}