add to 1.3 release notes #606

Job	Run time
build-macos-no-brew-Qt6 (clang-9)	18m 22s
build-macos-brew (clang-9)	5m 41s
build-linux (gcc-9)	15m 18s
build-linux-Qt6 (gcc-9)	13m 59s
build-macos-brew-Qt6 (clang-9)	14m 38s
build-macos-no-brew (clang-9)	13m 35s
build-windows-mingw (5.15.2)	10m 10s
build-windows-mingw-Qt6 (6.3.0, qtmultimedia qt5compat)	12m 59s
build-windows-vs (5.15.2)	9m 35s
build-windows-vs-Qt6 (6.3.0, qtmultimedia qt5compat)	12m 55s
	2h 7m 12s

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