backends: s/ilang/rtlil as a result of https://github.com/YosysHQ/yos… #3607

Job	Run time
document	47s
check-links	45s
smoke (amaranth-lang/amaranth-boards)	31s
test (3.8)	2m 51s
smoke (amaranth-lang/amaranth-stdio)	39s
test (3.9)	2m 17s
smoke (amaranth-lang/amaranth-soc)	38s
test (3.10)	2m 10s
test (3.11)	2m 42s
test (3.12)	3m 30s
test (pypy-3.8)	5m 8s
test (pypy-3.9)	4m 58s
test (pypy-3.10)	4m 47s
test (3.13-dev)	3m 6s
publish-docs	9s
publish-docs-dev	0s
required	1s
publish-package	21s
publish-schemas	11s
publish-release	0s
	35m 31s

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