Add Osu! 2021.323.0 (#9315)

manifests/Peppy/Osu!/2021.323.0.yaml

@@ -0,0 +1,17 @@
+Id: Peppy.Osu!
+Name: Osu!
+Publisher: Dean "peppy" Herbert
+AppMoniker: osu
+Description: "A free-to-win rhythm game developed by peppy with four game modes: osu!standard, a circle clicking simulator; osu!taiko, a drumming emulator; osu!catch, a fruit salad catcher; and osu!mania, a key smashing synthesizer."
+Homepage: https://osu.ppy.sh/
+Version: 2021.323.0
+License: MIT
+LicenseUrl: https://github.com/ppy/osu/blob/master/LICENCE
+Installers:
+  - Arch: x64
+    Url: https://github.com/ppy/osu/releases/download/2021.323.0/install.exe
+    Sha256: eaf4692a0cffdb13040c9c28f92f7587be3c05fe79e50995383d5d3d5b45cb2c
+    InstallerType: exe
+    Switches:
+      Silent: /silent
+      SilentWithProgress: /silent