Add git pull to upgrade command

[LuernOutOfOrder]

This pull request introduces a new git_pull function to handle pulling updates from a remote repository and integrates it into the upgrade_bin function. It also includes minor adjustments to imports to accommodate the new functionality.

New functionality:

• Added git_pull function in src/git/mod.rs to execute a git pull command and log an error if the pull operation fails.

Integration:

• Updated the upgrade_bin function in src/upgrade/mod.rs to call the new git_pull function, ensuring the repository is updated before proceeding with the upgrade process.

Import adjustments:

• Added imports for LogLevel and log_from_log_level in src/git/mod.rs to support logging in the git_pull function.
• Adjusted imports in src/upgrade/mod.rs to include the git module for accessing the new git_pull function.