Update Windows builds (AppVeyor) to new boost-ci (Windows library) release. Note Python 2 support was dropped in the boost-ci builds, so we still use the older version, 1.70.0, for Python 2.7 on Windows. Also updated the dev container Conda environment files.
Windows builds are still broken (see #355), but this update should allow the Python 3.8 CI to at least compile without errors.
Update Windows builds (AppVeyor) to new boost-ci (Windows library) release. Note Python 2 support was dropped in the boost-ci builds, so we still use the older version, 1.70.0, for Python 2.7 on Windows. Also updated the dev container Conda environment files.
Windows builds are still broken (see #355), but this update should allow the Python 3.8 CI to at least compile without errors.