add to 1.3 release notes #605

Job	Run time
build-macos-no-brew (clang-9)	15m 51s
build-macos-no-brew-Qt6 (clang-9)	15m 47s
build-linux-Qt6 (gcc-9)	17m 7s
build-linux (gcc-9)	16m 53s
build-macos-brew (clang-9)	5m 45s
build-macos-brew-Qt6 (clang-9)	7m 27s
build-windows-mingw (5.15.2)	14m 52s
build-windows-mingw-Qt6 (6.3.0, qtmultimedia qt5compat)	17m 46s
build-windows-vs (5.15.2)	9m 46s
build-windows-vs-Qt6 (6.3.0, qtmultimedia qt5compat)	14m 5s
	2h 15m 19s

Provide feedback