README: fix dependences requirement for macOS

[MeteorsLiu]

User may not install pkg-config when initalization.

When lacking of pkg-config tool, it will panic like that

panic: test link args ' $(pkg-config --libs bdw-gc); -lgc' failed
	expanded to: [-lgc]
	resolved to: [-lgc]
	error: ld: library 'gc' not found
clang: error: linker command failed with exit code 1 (use -v to see invocation)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.65%. Comparing base (03517ce) to head (c7e68da).
Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #937   +/-   ##
=======================================
  Coverage   97.65%   97.65%           
=======================================
  Files          22       22           
  Lines        6313     6313           
=======================================
  Hits         6165     6165           
  Misses        128      128           
  Partials       20       20           

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[cpunion]

doc/_readme/scripts/install_macos.sh need update