⬆️ Update babel requirement from ~=2.14.0 to ~=2.15.0

Updates the requirements on [babel](https://github.com/python-babel/babel) to permit the latest version.
- [Release notes](https://github.com/python-babel/babel/releases)
- [Changelog](https://github.com/python-babel/babel/blob/master/CHANGES.rst)
- [Commits](python-babel/babel@v2.14.0...v2.15.0)

---
updated-dependencies:
- dependency-name: babel
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements.txt

@@ -4,7 +4,7 @@ pyserial~=3.5         # Serial link to communicate with the display
 PyYAML~=6.0.1         # For themes files
 psutil~=5.9.8         # CPU / disk / network metrics
 pystray~=0.19.5       # Tray icon (all OS)
-babel~=2.14.0         # Date/time formatting
+babel~=2.15.0         # Date/time formatting
 ruamel.yaml~=0.18.6  # For configuration editor
 sv-ttk~=2.6.0         # Tk Sun Valley theme for configuration editor