GitAuto: Update pyqt5 to the latest version pyqt6

Resolves #1

What is the feature

Update the project dependencies and codebase from PyQt5 to the latest version, PyQt6.

Why we need the feature

Upgrading to PyQt6 brings several benefits:

Latest Features: Access to new widgets and functionalities introduced in PyQt6.
Performance Improvements: Enhanced performance optimizations over PyQt5.
Security Updates: Incorporation of security patches and fixes.
Compatibility: Better support for newer versions of Python and integration with modern libraries.
Maintenance: Reduces technical debt by keeping dependencies up to date.

Staying current with dependencies ensures the project remains robust, secure, and easier to maintain in the long run.

How to implement and why

Step 1: Update Dependency Files

Modify requirements.txt and requirements.pytorch.txt:
```
- PyQt5>=5.15.0
+ PyQt6>=6.0.0
```
This ensures that the project installs PyQt6 when setting up the environment.

Step 2: Update Import Statements

PyQt6 has reorganized modules and changed import paths.

Replace all PyQt5 imports in the codebase. For example:

# Before (PyQt5)
from PyQt5.QtWidgets import QApplication, QMainWindow

# After (PyQt6)
from PyQt6.QtWidgets import QApplication, QMainWindow

Adjust enums and flags, as some have moved or changed:

# Before (PyQt5)
alignment = Qt.AlignCenter

# After (PyQt6)
from PyQt6.QtCore import Qt
alignment = Qt.AlignmentFlag.AlignCenter

Step 3: Update Code for API Changes

Print Functionality: Ensure all print statements are compatible with Python 3 (use parentheses).
Signal and Slot Connections: Update any deprecated connection styles:
```
# Before (PyQt5)
button.clicked.connect(self.handle_click)

# After (PyQt6)
button.clicked.connect(self.handle_click)
```
(Connection syntax remains largely the same but check for any deprecations.)
Attribute and Method Changes: Some methods and properties may have been renamed or altered.
- Review the PyQt6 documentation for any classes used.
- Update method calls and property accesses accordingly.

Step 4: Test the Application

Run the application to identify any issues arising from the upgrade.
Pay special attention to:
- UI rendering issues.
- Event handling and signal-slot mechanisms.
- Any warnings or errors printed to the console.

Step 5: Update Documentation

Search for any references to PyQt5 in:
- README.md
- Documentation files in the doc/ directory.
Update these references to PyQt6 to reflect the changes.

Why This Approach

Systematic Updates: Breaking down the implementation into steps ensures a thorough upgrade.
Minimal Disruption: By carefully handling import and API changes, we reduce the risk of introducing bugs.
Maintainability: Updating documentation keeps users and contributors informed, easing future development.

About backward compatibility

Breaking Changes: Upgrading to PyQt6 introduces changes that are not backward compatible with PyQt5.
Python Version Requirement: PyQt6 requires Python 3.6 or newer.
Decision: Since the benefits outweigh the drawbacks, and assuming our user base is able to upgrade, we accept the loss of backward compatibility with PyQt5.
Alternative Options:
- Dual Support: Attempting to support both PyQt5 and PyQt6 increases complexity and is not recommended.
- Separate Branch: Maintain a separate branch for PyQt5 support if necessary.

By proceeding with the upgrade, we acknowledge that users will need to have an environment compatible with PyQt6, which is aligned with keeping the project modern and up to date.

Test these changes locally

git checkout -b gitauto/issue-#1-1bf02638-e939-4ac6-a566-d18707d0cc18
git pull origin gitauto/issue-#1-1bf02638-e939-4ac6-a566-d18707d0cc18

hiroshinishio / tetris