feat: tmpo [-v | --version | --version] now notifies when update available

[DylanDevelops]

Pull Request Checklist

• I have read and followed the contribution guidelines.
• My pull request targets the main branch of tmpo.
• I have tested these changes locally on my machine.

Closes #24

Description

This pull request adds automatic update checking to the CLI tool, so users are notified if a newer version is available when running the version command or using the -v/--version flag. The implementation includes a new internal package for update logic, refactors how version information is displayed, and introduces robust version comparison and testing.

Update notification feature:

• Added a new internal package internal/update/checker.go that checks for internet connectivity, fetches the latest release from GitHub, compares semantic versions, and determines if an update is available.
• Introduced the DisplayVersionWithUpdateCheck function in cmd/version.go to display version info and check for updates, used by both the version subcommand and the new version flag.
• Added a checkForUpdates helper in cmd/version.go that uses the update package to notify the user if a newer release is available, handling errors silently.

CLI improvements:

• Changed the root command in cmd/root.go to support a -v/--version flag, which now triggers the update check and version display, instead of only showing static version info. [1] [2]

Testing and reliability:

• Added comprehensive unit tests for version comparison and internet connectivity in internal/update/checker_test.go to ensure correct update detection logic.

Screenshots

Out of date with internet connection:

Out of date without an internet connection: