Bump project version to 5.0.0b5

Update pyproject.toml to change the project version from 4.9.7 to 5.0.0b5, marking a beta/pre-release for the upcoming 5.0 release cycle.

Bump package version to 5.0.0b4

Update __version__ in ytsage/__init__.py from 5.0.0b3 to 5.0.0b4 to mark the next beta release.

Bump version to 5.0.0b3

Update package version in ytsage/__init__.py from 5.0.0b2 to 5.0.0b3 to reflect a new beta release.

Include PySide6.QtNetwork in build workflows

Moved PySide6.QtNetwork from the excludes to the includes list in build workflows for Linux, macOS, and Windows. This ensures the QtNetwork module is bundled during packaging.

Update badge labels in README

Changed the 'pypi downloads' and 'github downloads' badge labels to 'downloads' for consistency and improved readability.

Add Flatpak badge to Linux install options

Included a Flathub badge in the Linux installation table to indicate Flatpak bundle availability.