Add a dependency to the corresponding rule
void add_dependency(Rule *current_rule, Rule *dep_rule, char *token){
    Rule *curr;
    Dependency *dep = malloc(sizeof(Dependency));
    dep->rule = dep_rule;
    dep->next_dep = NULL;

    if (current_rule->dependencies == NULL) {
        current_rule->dependencies = dep;
    } else {
        curr = current_rule;
        while (curr->dependencies != NULL) {
            curr = curr->next_rule;
        }
        curr->dependencies->next_dep = dep->next_dep;
    }
}