Naz

- add target level to Breachandler: https://github.com/komuw/naz/pull/163

- make available to `hooks` the raw pdu as sent/received to/from SMSC: https://github.com/komuw/naz/pull/159
- rename the `naz.hooks.BaseHook` methods: https://github.com/komuw/naz/pull/159
The new names are more correct and indicate what is actually taking place.
- use github actions for CI: https://github.com/komuw/naz/pull/162
- Add heartbeat to BreachHandler: https://github.com/komuw/naz/pull/161

- make sure that `naz` reads exactly the first 4bytes of an smpp header: https://github.com/komuw/naz/pull/153
- if `naz` is unable to read exactly those bytes, it unbinds and closes the connection
- this is so as to ensure that `naz` behaves correctly and does not enter into an inconsistent state.
- make sire that `naz` reads exacly the first 16bytes of the smpp header: https://github.com/komuw/naz/pull/155
- this builds on the [earlier work](https://github.com/komuw/naz/pull/153) but now `naz` takes it a step further and will unbind & close connection if it is unable to read the entire SMPP header
- this is done to prevent inconsistency and also to try and be faithful to the smpp spec.
- enhance type annotations of `naz.log`: https://github.com/komuw/naz/pull/156

- Simplify Breach log handler: https://github.com/komuw/naz/pull/152

- added a logging BreachHandler: https://github.com/komuw/naz/pull/149
- renamed `naz.logger` to `naz.log`: https://github.com/komuw/naz/pull/150
- fix documentation styling: https://github.com/komuw/naz/pull/151

- added static analysis support using pytype: https://github.com/komuw/naz/pull/148