Disable NuGet uploading of releases for now (#2450)

* Add --skip-duplicate to NuGet upload

This is necessary to avoid problems when we release a new version of
Dafny but don't change the version of the runtime.

* Temporarily disable NuGet uploads during release

Unfortunately, the NuGet packages generated by this script have overly
strict .NET version dependencies, and we don't yet know how to fix this.

See #2423

Author: atomb

.github/workflows/publish-release-reusable.yml

@@ -124,4 +124,7 @@ jobs:
 
     - name: Upload package to NuGet
       if: ${{ inputs.release_nuget }}
-      run: dotnet nuget push "dafny/Binaries/Dafny*.nupkg" -k ${{ secrets.nuget_api_key }} -s https://api.nuget.org/v3/index.json
+      # Need --skip-duplicate for cases where we release a new Dafny
+      # version but the runtime hasn't changed and is still the old
+      # version.
+      run: dotnet nuget push --skip-duplicate "dafny/Binaries/Dafny*.nupkg" -k ${{ secrets.nuget_api_key }} -s https://api.nuget.org/v3/index.json

.github/workflows/publish-release.yml

@@ -33,7 +33,10 @@ jobs:
       sha: ${{ github.sha }}
       tag_name: ${{ github.ref }}
       draft: true
-      release_nuget: true
+      # Currently automated NuGet uploads have overly strict .NET
+      # version dependencies. Skipping until that's fixed. See here:
+      # https://github.com/dafny-lang/dafny/issues/2423
+      release_nuget: false
       # We can probably automate pulling this out of RELEASE_NOTES.md in the future
       release_notes: ""
     secrets: