Work around issue with brew and opam #763

Job	Run time
docker-master	1h 30m 3s
publish-standalone-dry-run	14s
test-standalone (master, dev, default)	1m 24s
build-js-of-ocaml (master, 4.11.1)	13m 4s
validate-docker-master	2m 40s
build-wasm-of-ocaml (master, 4.14.1)	17m 12s
generated-files (master)	24m 14s
standalone-haskell (master)	47m 52s
test-amd64	2h 17m 39s
deploy-js-wasm-of-ocaml	29s
docker-check-all	3s
	5h 34m 54s

Provide feedback