Update greeting in main.go based on issue comments

[sergeyklay]

Read the comments on this issue using the tracker_api tool to find the greeting name and language. Then update main.go to greet the user with that name in that language.

Do not hardcode anything. The name and language must come from the issue comments.

Acceptance criteria:

• main.go prints a greeting using the name and language found in comments
• go build ./... succeeds

[sergeyklay]

The greeting name should be: Serghei

[sergeyklay]

Use Ukrainian language for the greeting. "Привіт" is hello in Ukrainian.