NuGetPackageDownloader: Only verify signing on windows

Author: edvilme

src/Cli/dotnet/NugetPackageDownloader/NuGetPackageDownloader.cs

@@ -65,7 +65,7 @@ public NuGetPackageDownloader(
             _restoreActionConfig = restoreActionConfig ?? new RestoreActionConfig();
             _retryTimer = timer;
             _sourceRepositories = new();
-            _verifySignatures = verifySignatures;
+            _verifySignatures = OperatingSystem.IsWindows() && verifySignatures; // TODO: Check
 
             _cacheSettings = new SourceCacheContext
             {
@@ -131,7 +131,6 @@ public async Task<string> DownloadPackageAsync(PackageId packageId,
             }
 
             await VerifySigning(nupkgPath, repository);
-            
             return nupkgPath;
         }