Add 3.4 to branches list

.github/workflows/artifacts.yml

.github/workflows/bootstrap.yml

.github/workflows/linux.yml

.github/workflows/macos.yml

.github/workflows/quick-jobs.yml

.github/workflows/windows.yml

boot/ci-artifacts.template.yml

boot/ci-bootstrap.template.yml

boot/ci-linux.template.yml

boot/ci-macos.template.yml

boot/ci-quick-jobs.template.yml

boot/ci-windows.template.yml