v0.3.4

Added

• Two gates now stand between a release commit and its tag, because v0.3.3
  was tagged on a red build. scripts/release.sh first installs the package
  into an empty virtualenv and runs the suite there, before anything is
  committed — a working checkout cannot tell a declared dependency from one
  that merely happens to be installed, which is exactly how pyserial went
  undeclared. It then pushes the release commit and waits for every workflow
  run on that exact SHA to conclude successfully before creating the tag, so a
  tag on a red build is structurally impossible rather than merely
  discouraged. If CI fails, main is left carrying an untagged commit, which
  is an ordinary state to fix forward from. --skip-venv and --skip-ci exist
  for emergencies.

Fixed

• CI could not collect the acceptance tests. Dropping CI's
  --ignore=tests/acceptance in 0.3.3 exposed that pyserial was never
  declared anywhere: tests/acceptance/helpers.py imports it at module scope,
  so collection died with ModuleNotFoundError: No module named 'serial' even
  though those tests skip themselves without a --port. It went unnoticed
  locally because PlatformIO's environment already provides the module. Now
  declared in the dev extra, and verified by running CI's exact command in a
  clean virtualenv rather than the working one.