The most significant changes in the code include the update of the Python version used in the project, the addition of a new folder, and the implementation of new modules in the main.py file. The Python version has been updated from 3.9 to 3.12, which is reflected in the Basis.pyproj file. A new folder named "CustomModules" has been added to the project. In the main.py file, the `time` and `datetime` modules have been imported, replacing the `timedelta` module. The start time of the program and the bot is now being recorded, and the uptime of the bot is being calculated using the `datetime` module. The `pip` module has been added to the requirements.txt file. Lastly, the README.md file has been updated to specify the new Python version requirement.

1. Python version updated from 3.9 to 3.12 in the Basis.pyproj file.
2. Added a new folder "CustomModules" to the project.
3. Imported `time` module in main.py to record the start time of the program.
4. Replaced `timedelta` module with `datetime` module in `aclient` class in main.py.
5. Start time of the bot is now recorded in UTC format and logged in `aclient` class in main.py.
6. Bot uptime is calculated using `datetime` module in `self` function in main.py.
7. Added `pip` module to requirements.txt file.
8. Updated README.md file to specify Python version 3.11 or higher requirement.