ci: disable Go bindings CI for macos for now #393

Job	Run time
macos-latest, cmake, gcc, easy backend	41s
macos-latest, cmake, gcc, gmp backend	44s
macos-latest, cmake, clang, easy backend	43s
macos-latest, cmake, clang, gmp backend	39s
macos-latest, autotools, gcc, easy backend	1m 0s
macos-latest, autotools, gcc, gmp backend	1m 25s
macos-latest, autotools, clang, easy backend	57s
macos-latest, autotools, clang, gmp backend	56s
ubuntu-20.04, cmake, gcc, easy backend	1m 33s
ubuntu-20.04, cmake, gcc, gmp backend	1m 28s
ubuntu-20.04, cmake, clang, easy backend	1m 38s
ubuntu-20.04, cmake, clang, gmp backend	1m 38s
ubuntu-20.04, autotools, gcc, easy backend	2m 21s
ubuntu-20.04, autotools, gcc, gmp backend	2m 11s
ubuntu-20.04, autotools, clang, easy backend	2m 6s
ubuntu-20.04, autotools, clang, gmp backend	2m 25s
	22m 25s

Provide feedback