[CI] Remove non-installable .NET versions.

Author: vyazelenko

.github/workflows/ci.yml

@@ -85,7 +85,7 @@ jobs:
  strategy:
  fail-fast: false
  matrix:
- dotnet: [ '8', '9', '10', '11', '12', '13' ]
+ dotnet: [ '8', '9', '10' ]
  env:
  DOTNET_SKIP_FIRST_TIME_EXPERIENCE: true
  DOTNET_CLI_TELEMETRY_OPTOUT: 1