Building shared libraries on Windows fails

The setup in the README_SETUP.md does not work.

See doc/Install_develop.rst

How to build on Windows
~~~~~~~~~~~~~~~~~~~~~~~

We use `Visual Studio
2019 <https://visualstudio.microsoft.com/de/vs/features/cplusplus/>`__
as compiler. We use `cmake <https://cmake.org/download/>`__ as build
tool.

1. clone/update the subrepo ``git submodule update --init proto``
2. ``mkdir build``
3. ``cd build``
4. ``conan install .. -g visual_studio -s arch=x86_64 -s build_type=Release -s compiler.toolset=v142 -s compiler.version=16 -s compiler.runtime=MD --build=missing --update``
5. ``cmake -B . ..``
6. open ``libcaosdb.sln`` with Visual Studio, change the buildtype to
   ``Release`` and build the project. (You can open Tools/Command
   Line/Developer Command Prompt and execute
   ``msbuild libcaosdb.sln /property:Configuration=Release``)