[ci] removed temp fix for missing package (#2493)

.appveyor.yml

-version: 2.3.1.{build}
+version: 2.3.1.{build}
 
 image: Visual Studio 2015
 platform: x64
@@ -54,5 +54,5 @@ test_script:
         if (!$?) { $host.SetShouldExit(-1) }
       }  # run all examples
   - cd %APPVEYOR_BUILD_FOLDER%\examples\python-guide\notebooks
-  - conda install -q -y -n test-env ipywidgets notebook pywin32
+  - conda install -q -y -n test-env ipywidgets notebook
   - jupyter nbconvert --ExecutePreprocessor.timeout=180 --to notebook --execute --inplace *.ipynb  # run all notebooks

.ci/test_windows.ps1

@@ -49,6 +49,6 @@ if ($env:TASK -eq "regular") {
     python $file ; Check-Output $?
   }  # run all examples
   cd $env:BUILD_SOURCESDIRECTORY/examples/python-guide/notebooks
-  conda install -q -y -n $env:CONDA_ENV ipywidgets notebook pywin32
+  conda install -q -y -n $env:CONDA_ENV ipywidgets notebook
   jupyter nbconvert --ExecutePreprocessor.timeout=180 --to notebook --execute --inplace *.ipynb ; Check-Output $?  # run all notebooks
 }

.vsts-ci.yml

@@ -116,13 +116,13 @@ jobs:
     matrix:
       regular:
         TASK: regular
-        PYTHON_VERSION: 3.5
+        PYTHON_VERSION: 3.7
       sdist:
         TASK: sdist
         PYTHON_VERSION: 2.7
       bdist:
         TASK: bdist
-        PYTHON_VERSION: 3.6
+        PYTHON_VERSION: 3.5
   steps:
   - powershell: Write-Host "##vso[task.prependpath]$env:CONDA\Scripts"
     displayName: Enable conda