src/class/cdc: don't flush pending data in cdcd_open

Fixes issue hathach#3807

Signed-off-by: Damien George <damien@micropython.org>

docs: convert changelog release notes from RST to Markdown (hathach#3746

)

* docs: convert changelog release notes from RST to Markdown

Merge pull request hathach#3350 from hathach/update-changelog

update changelog.rst

Merge pull request hathach#3276 from hathach/release-0.19.0

update for release 0.19.0

Merge pull request hathach#2913 from hathach/release-0.18.0

update doc, bump up release 0.18.0

Merge pull request hathach#2801 from hathach/release-0.17.0

Merge pull request hathach#2343 from hathach/release-0.16.0

Release 0.16.0

Merge pull request hathach#1890 from hathach/release-0.15.0

update version to 0.15.0

Merge pull request hathach#1609 from hathach/release-0.14.0-p2

update repository.yml

Merge pull request hathach#1341 from hathach/release-0.13.0

increase version, update doc for release