No parallel compile on Windows

Author: jonashaag

.github/actions/build_pandas/action.yml

@@ -18,7 +18,9 @@ runs:
       run: |
         which python
         which pip
-        time python setup.py build_ext -v -j 3
+        # Cannot use parallel compilation on Windows, see https://github.com/pandas-dev/pandas/issues/30873
+        j=${{ runner.os == 'Windows' ? 1 : 3 }}
+        time python setup.py build_ext -v -j $j
         pip install -v -e . --no-build-isolation --no-use-pep517 --no-index
       shell: bash -el {0}