Remove `Formula` (#327) #1176

Job	Run time
build (macos-latest)	6m 22s
build (ubuntu-latest)	6m 39s
build-docker	8m 49s
gillian_c2_tests (ubuntu-latest)	2m 4s
gillian_c_tests (ubuntu-latest)	6m 18s
gillian_js_tests (ubuntu-latest)	2m 53s
test262	0s
collections-c	0s
deploy-docs (ubuntu-latest)	8s
	33m 13s

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