Specifically require dotnet core 2.1.4 in an attempt to fix weird Kokoro issue.
Specifically require dotnet core 2.1.4 in an attempt to fix weird Kokoro issue.

jsimonweb/csharp-docs-samples,GoogleCloudPlatform/dotnet-docs-samples,GoogleCloudPlatform/dotnet-docs-samples,GoogleCloudPlatform/dotnet-docs-samples,GoogleCloudPlatform/dotnet-docs-samples,jsimonweb/csharp-docs-samples,jsimonweb/csharp-docs-samples,jsimonweb/csharp-docs-samples