Update supported Alpine version to 3.17 and later

[SeanTAllen]

With Alpine 3.17, Alpine stopped supporting libexecinfo. In the process,
the backtrace functionality was moved into musl directly. This makes it
very hard to support both pre and post 3.17 Alpine with the compiler.

We decided to not support 3.16 and earlier as it is a decent amount of
work to support both and 3.16 is EOL in about 9 months.

As part of the change, we are updating our public docker images to be
compatiable with the change. Our public Alpine images are now based off
of Alpine 3.18.

[SeanTAllen]

As of alpine 3.17, there is no longer an execinfo package. We now have backtrace functionality without it.

If we follow the path of this PR, ponyc would no longer compile programs on earlier alpine's.

3.16's end of support is 2024-05-23 and it is currently receiving only bug fixes. I think given the hoops we need to jump through to support 3.16 and 3.17 and the less than a year til 3.16 is done, we should drop support for earlier alpine's and say 3.17 and later.

The current state of affairs is that without patching similar to this PR, you can't use ponyc on Alpine 3.17 and 3.18

[jemc]

Agreed on dropping support for Alpine 3.16 to avoid complexity 👍

[SeanTAllen]

This doesn't get a changelog as it needs two entries. I've manually included the updates.

[SeanTAllen]

The timing on merging this is tricky as other images that we use for CI are based off this and might need to be updated accordingly. Once this is approved, I'll get everything else in order and do all the updates as needed.