Release 0.56.0

[enh] Add 0.56.0 changes to CHANGELOG.md

CHANGELOG.md

+## [v0.56.0](https://git.duniter.org/clients/python/duniterpy/-/milestones/10) (20th January 2020)
+### Code
+- #58, !84: Introduce WS2P API support: **BREAK BACKWARD COMPATIBILITY**:
+  - `bma.ws`: now websocket connections use the special `WSConnection` class and `async`, check examples.
+  - Add two examples, a helper to retrieve the WS2P API from BMA.
+- #113, !89: Blocks signature verification is correctly handled now, differently from other documents.
+- #112, !88: fix `Unlock.from_inline()` error on a newly created Unlock
+- !87: Typos in Block: `noonce` −> `nonce`, hash
+- !82: Use `sys.exit()` instead of `exit()`
+- !79:
+  - Move tools out of the `helper` folder
+  - Dedicate the `helper` folder to helpers
+  - Introduce `output_available()` helper to check if an output is available
+
+### Dependencies
+- !91: fix the `attrs`/`attr` dependency
+
+### Build
+- #107, !81: Enhance version definition in `setup.py`
+
+### CI/CD
+- !78: Release on PyPI only on tags
+
+### Documentation
+- #101, !80: Publish auto-documentation on GitLab Pages
+- #106, !83: Migrate the `README` back to markdown, reword and update it.
+- !77: Improve v0.55.0 and add v0.55.1 changelog
+- !92: Add v0.56.0 changelog
+---
+
+- Thanks @vtexier, @Moul
+
 ## v0.55.1 (19th July 2019)
 - #102: wheel build does not longer include `duniterpy` sub-folders
 - Trigger release only on `master` not on tag as protected environment variables are not shared with pipelines started on a tag
@@ -19,7 +51,7 @@
 - Add `format` and `check-format` commands to the `MakeFile`
 - !63: Format the code with Black
 
-#### Other
+#### Others
 - `Makefile`: `check` command for `mypy`, `pylint`, and `check-format` checks
 - #94: Apply Mypy, Pylint and Black on `tests` and `examples` folders