Update nightly.yaml to match release.yml NuGet tool installer changes (#7810)

* Initial plan

* Update nightly.yaml to match release.yml NuGet tool installer changes

Co-authored-by: NikolajBjorner <[email protected]>

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: NikolajBjorner <[email protected]>

Author: Copilot

scripts/nightly.yaml

@@ -254,9 +254,9 @@ stages:
       inputs:
         artifact: 'MacArm64'
         path: $(Agent.TempDirectory)\package
-    - task: NuGetToolInstaller@0
+    - task: NuGetToolInstaller@1
       inputs:
-        versionSpec: 5.x
+        versionSpec: 6.x
         checkLatest: false        
     - task: PythonScript@0
       displayName: 'Python: assemble files'
@@ -302,9 +302,9 @@ stages:
       inputs:
         artifact: 'WindowsBuild-x86'
         path: $(Agent.TempDirectory)\package
-    - task: NuGetToolInstaller@0
+    - task: NuGetToolInstaller@1
       inputs:
-        versionSpec: 5.x
+        versionSpec: 6.x
         checkLatest: false        
     - task: PythonScript@0
       displayName: 'Python: assemble files'