Fix coro::when_all not compiling when passing the output of std::views

Fixes a bug that prevents coro::when_all from compiling when passing the result of a std::ranges::views of awaitables. The for-each loop in coro::when_all defines an auto& a when looping through awaitables, when it should use auto&& a since it's moving them into a vector.

Here is a minimal example that should compile, but currently doesn't.

#include <iostream>
#include <ranges>

#include <coro/coro.hpp>

static coro::task<void> foo(int i)
{
    std::cout << i << '\n';
    co_return;
}

int main(void)
{
    coro::sync_wait(coro::when_all(
        std::views::iota(0, 6)
        | std::views::transform(::foo)
    ));
    return 0;
}

Also there's a bug in your .githooks that changes all & in the code portions of your README to ${EXAMPLE_CORO_TASK_CPP}. I haven't fixed that, but you I thought you should know.

jbaldwin / libcoro

Fix coro::when_all not compiling when passing the output of std::views #209