cleanup: Normalise audio to -1.0 dB. #1259

Job	Run time
Fedora with ASAN	0s
Alpine (static)	0s
Alpine	0s
Clang-Tidy	0s
Check for translatable strings	0s
Update nightly release tag	4s
Debian	0s
Docs	1m 54s
macOS user	0s
Ubuntu LTS	0s
Flatpak	4m 43s
Android (armeabi-v7a, Debug, 6.2.4)	3m 38s
macOS distributable (arm64)	3m 12s
Windows (i686, Debug)	5m 9s
Android (armeabi-v7a, Debug, 6.8.1)	3m 51s
macOS distributable (x86_64)	7m 0s
Windows (i686, Release)	5m 2s
Android (armeabi-v7a, Release, 6.2.4)	3m 19s
Windows (x86_64, Debug)	5m 32s
Android (armeabi-v7a, Release, 6.8.1)	3m 51s
Windows (x86_64, Release)	5m 22s
Android (arm64-v8a, Debug, 6.2.4)	3m 30s
Android (arm64-v8a, Debug, 6.8.1)	4m 43s
Android (arm64-v8a, Release, 6.2.4)	3m 16s
Android (arm64-v8a, Release, 6.8.1)	3m 39s
Test macOS distributable (arm64)	10s
Test macOS distributable (x86_64)	22s
	1h 8m 17s

Provide feedback