Jenkins: Add STDERR to console workaround

I'm not even sure why this is a problem. Whenever STDOUT or STDERR
aren't redirected, the Python process fails with

Fatal Python error: init_sys_streams: can't initialize sys standard streams
OSError: [WinError 6] Invalid handle

Jenkinsfile

@@ -110,7 +110,7 @@ def windowsBuildCommands() {
                 wine py -m pip install -e .[css] &&
                 cd scripts &&
                 wine py -m PyInstaller -y dosage.spec;
-                wineserver -w" | tee log.txt
+                wineserver -w" 2>&1 | tee log.txt
         '''
         archiveArtifacts '*/scripts/dist/*'
     }