Release 8.3.0

[danirabbit]

Todo:

• Release Gala 8.3.0
• Default to building workspace switcher #492
• IconGroup: change focused style #439
• Make sure this runs okay on stable. No crashes etc

[danirabbit]

@lenemter @leolost2605 Any objections to releasing this? :)

[leolost2605]

Maybe the focus behavior of the new workspace icon? It's kinda throwing me of sometimes that the focus just disappears and shouldn't be much work I think? I could do this tomorrow but I'd also be fine with releasing as is :)

[leolost2605]

#506