Microsoft.OpenApi.Readers.dll no longer digitally signed #941

As of the 1.3.1 NuGet release package for Microsoft.OpenApi.Readers, it appears the Microsoft.OpenApi.Readers.dll library contained within is no longer being digitally signed.

To reproduce:

1. Download the latest (1.3.2) or previous (1.3.1) version of the Microsoft.OpenApi.Readers package.
2. Extract the contents locally and navigate to lib\netstandard2.0.
3. Inspect the Properties of Microsoft.OpenApi.Readers.dll.

Observed result: The "Digital Signatures" tab is not present, and the DLL is not signed.

Expected result: The "Digital Signatures" tab is present, and the DLL is signed.

Example (note the lack of a Digital Signatures tab):

Looking back at the previous 1.2.3 version, this was being signed: