build: match windows CI and Release build steps

After a recent LLVM tag update, the Windows Release build failed even
though pre- and post-merge Windows CI builds passed.  This patch makes
the Windows Release build use the same flags as the Window CI build to
try and address the Release build failures in the future.

setup.py

@@ -77,6 +77,7 @@ class CMakeBuild(build_py):
             cmake_args = [
                 f"-DCMAKE_BUILD_TYPE=Release",
                 f"-DPython3_EXECUTABLE={sys.executable}",
+                f"-DPython3_FIND_VIRTUALENV=ONLY",
                 f"-DLLVM_TARGETS_TO_BUILD=host",
                 f"-DMLIR_ENABLE_BINDINGS_PYTHON=ON",
                 f"-DLLVM_ENABLE_PROJECTS=mlir",