v1.0.0-beta.4

Here comes the fourth beta release of Pods 1.0.0 with the following changes:

• The blurry symbolic application icon has been fixed, thanks to @allaeddineomc.
• A status page is now displayed if there are no images, containers or pods.
• The style has been improved, in particular, there is now better differentiation between light, dark and high contrast modes.
• The feature for coloring the header bar has been removed. It will hopefully come back when there is API support for it.
• A lot of smaller UI improvements have been implemented to give Pods a more polished look.
• The flatpak runtime has been updated to version 43.
• Improvements in infrastructure like an issue template have landed, thanks to @vv9k.
• Image downloads can now be aborted.
• Arguments can now be added to a container command, thanks to @vv9k.
• It's now possible to set labels on images, containers and pods, thanks to @vv9k.
• Translation updates