Add UsePython Task in Nuget Publish workflow (#21144)

### Description
Otherwise it would fail in 

https://github.com/microsoft/onnxruntime/blob/b95982e588e2d433958aa9aa82557b714ec4e3de/tools/ci_build/github/azure-pipelines/publish-nuget.yml#L78-L81



### Motivation and Context
The Windows CPU image is migrated  to managed image


### Verification Link
https://dev.azure.com/aiinfra/Lotus/_build?definitionId=1313

Author: mszhanyi

tools/ci_build/github/azure-pipelines/publish-nuget.yml

@@ -29,6 +29,12 @@ stages:
 
     - checkout: self
       submodules: false
+
+    - task: UsePythonVersion@0
+      inputs:
+        versionSpec: '3.9'
+        addToPath: true
+
     - template: templates/set-version-number-variables-step.yml
 
     - script: mkdir "$(Build.BinariesDirectory)\nuget-artifact\final-package"