Make pyproject.toml the source for build dependencies #4372

Job	Run time
List changed packages	1m 44s
site	0s
test / linux (ubuntu-focal, standard)	2m 5s
test / linux (ubuntu-focal, minimal)	1m 30s
test / linux (ubuntu-jammy, standard)	1m 43s
test / linux (ubuntu-jammy, minimal)	2m 56s
test / linux (ubuntu-mantic, standard)	1m 38s
test / linux (ubuntu-mantic, minimal)	2m 28s
test / linux (debian-bullseye, standard)	1m 54s
test / linux (debian-bullseye, minimal)	1m 33s
test / linux (debian-bookworm, standard)	1m 41s
test / linux (debian-bookworm, minimal)	1m 45s
test / linux (fedora-30, standard)	1m 36s
test / linux (fedora-30, minimal)	1m 40s
test / linux (fedora-38, standard)	1m 51s
test / linux (fedora-38, minimal)	1m 35s
test / linux (gentoo-python3.11, standard)	2m 23s
test / linux (gentoo-python3.11, minimal)	3m 19s
test / linux (debian-bullseye-i386, standard)	1m 42s
test / linux (debian-bullseye-i386, minimal)	3m 27s
	38m 30s

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