Update runtime to 25.08 and SDK version to 21 in manifest#203

MrScratchcat wants to merge 1 commit intosonicnext-dev:mainsonicnext-dev/MarathonRecomp:mainfrom

MrScratchcat:flatpak-to-25.08MrScratchcat/MarathonRecomp:flatpak-to-25.08Copy head branch name to clipboard