Remove `-s` option from `which` in test script
Remove `-s` option from `which` in test script

When I tried running the tests with a debugger, the script failed with the following message:

    Illegal option -s
    Usage: /usr/bin/which [-a] args
    Illegal option -s
    Usage: /usr/bin/which [-a] args
    No debugger found

In case this `-s` flag is needed for other OSes than Linux (I'm working with Ubuntu 18.04), this could be based on a `uname` check (like on line 44).
tree-sitter/tree-sitter,tree-sitter/tree-sitter,tree-sitter/tree-sitter,tree-sitter/tree-sitter,tree-sitter/tree-sitter,tree-sitter/tree-sitter,tree-sitter/tree-sitter