Add Alpine to CI

[A5rocks]

Ref: #2885

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (7cb15ea) 99.64% compared to head (b5a8e1c) 99.64%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2933   +/-   ##
=======================================
  Coverage   99.64%   99.64%           
=======================================
  Files         116      116           
  Lines       17506    17506           
  Branches     3148     3148           
=======================================
  Hits        17444    17444           
  Misses         43       43           
  Partials       19       19           

Files	Coverage Δ
src/trio/_tests/test_socket.py	100.00% <100.00%> (ø)

[jakkdl]

Skimmed the test logs, and IPv6 tests are being skipped

  SKIPPED [1] ../.venv/lib/python3.11/site-packages/trio/_tests/test_dtls.py:87: need IPv6

probably not a big deal, but would be nice if it was possible to enable ipv6.

So other than the minor stuff, looks great!

[A5rocks]

Doesn't look like we can do IPv6. Making the socket works, but binding fails. It seems that this is a docker thing and that we'd need to configure the docker daemon? I found this stackoverflow post but it has no answers: https://stackoverflow.com/questions/75205327/configuring-docker-daemon-for-github-actions

Edit: also I removed musl-dev because #2939 should make that dependency not required.

[jakkdl]

Doesn't look like we can do IPv6. Making the socket works, but binding fails. It seems that this is a docker thing and that we'd need to configure the docker daemon? I found this stackoverflow post but it has no answers: https://stackoverflow.com/questions/75205327/configuring-docker-daemon-for-github-actions

Seems quite doable in theory then, but not worth the effort.