Updating UbuntuNetCoreKeyring dockerfile to use net core 5 (#17980)
Updating UbuntuNetCoreKeyring dockerfile to use net core 5 (#17980)

* Updating UbuntuNetCoreKeyring dockerfile to use net core 5

* Update ubuntu netcore keyring dockerfile to use net 5

* adding python to installed packages

Co-authored-by: Ben Broderick Phillips <543d5725ecc592e5b2d165e48c254308f058c13e@microsoft.com>
jackmagic313/azure-sdk-for-net,jackmagic313/azure-sdk-for-net,jackmagic313/azure-sdk-for-net,jackmagic313/azure-sdk-for-net,AsrOneSdk/azure-sdk-for-net,ayeletshpigelman/azure-sdk-for-net,AsrOneSdk/azure-sdk-for-net,ayeletshpigelman/azure-sdk-for-net,AsrOneSdk/azure-sdk-for-net,ayeletshpigelman/azure-sdk-for-net,AsrOneSdk/azure-sdk-for-net,ayeletshpigelman/azure-sdk-for-net,jackmagic313/azure-sdk-for-net