Fix max lenght in UDP port string (backport #315)

[mergify]

---

This is an automatic backport of pull request #315 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of aa15666 has failed:

On branch mergify/bp/humble/pr-315
Your branch is up to date with 'origin/humble'.

You are currently cherry-picking commit aa15666.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   rmw_microxrcedds_c/include/rmw_microros/rmw_microros.h
	modified:   rmw_microxrcedds_c/src/rmw_graph.c
	modified:   rmw_microxrcedds_c/src/rmw_init.c
	modified:   rmw_microxrcedds_c/src/rmw_microros/init_options.c

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   .github/workflows/ci.yml

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally