Replaces asyncio timeout with bespoke timeout function

[breca]

As per title, replaces asyncio.timeout function with a bespoke timeout function.

In conjunction with this PR this satisfies all but 3.8 test criteria.

Compiling 'podman_compose.py'...
************* Module podman_compose
podman_compose.py:2259:8: C0103: Variable name "s" doesn't conform to snake_case naming style (invalid-name)
podman_compose.py:2377:12: E1123: Unexpected keyword argument 'name' in function call (unexpected-keyword-arg)
podman_compose.py:2442:12: E1123: Unexpected keyword argument 'name' in function call (unexpected-keyword-arg)

-----------------------------------
Your code has been rated at 9.94/10

I wrote this before seeing that there was work being done in devel-asyncio, understand you're probably taking a different direction so feel free to ignore, but I already did the work so I thought I'd at least offer it. 😆

[breca]

Cleaner approach in #869

Closing

[p12tic]

@breca I actually think that this PR is a better approach because it doesn't introduce an additional dependency. Since some people will want to use podman-compose as standalone script, the number of dependencies should be minimized.

[p12tic]

Looks good to me, thanks! The PR just needs a rebase.