docs/changes: update for next release. #3609

Job	Run time
check-links	54s
document	50s
smoke (amaranth-lang/amaranth-boards)	35s
test (3.8)	2m 46s
smoke (amaranth-lang/amaranth-stdio)	43s
test (3.9)	2m 48s
smoke (amaranth-lang/amaranth-soc)	41s
test (3.10)	2m 43s
test (3.11)	3m 6s
test (3.12)	3m 40s
test (pypy-3.8)	6m 7s
test (pypy-3.9)	5m 42s
test (pypy-3.10)	5m 34s
test (3.13-dev)	4m 33s
publish-docs	33s
publish-docs-dev	0s
required	1s
publish-package	14s
publish-schemas	7s
publish-release	0s
	41m 37s

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