CHANGELOG: update for 5.6-rc0 #1594

Job	Run time
coverity-test	0s
coverage-test	7m 6s
master-tss-build-test (gcc)	28m 2s
build-test (ubuntu-18.04, gcc)	6m 55s
master-tss-build-test (clang)	6m 6s
build-test (ubuntu-18.04, clang)	8m 29s
build-test (ubuntu-20.04, gcc)	7m 9s
build-test (ubuntu-20.04, clang)	6m 9s
build-test (fedora-30, gcc)	7m 7s
build-test (fedora-30, clang)	6m 23s
build-test (opensuse-leap, gcc)	7m 23s
build-test (opensuse-leap, clang)	6m 30s
build-test (fedora-32, gcc)	7m 39s
build-test (fedora-32, clang)	6m 1s
build-test (ubuntu-22.04, gcc)	12m 56s
build-test (ubuntu-22.04, clang)	12m 11s
	2h 16m 6s

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