Log Message:
chat/lurch-purple: Update to 0.7.0

Actually works with pidgin, talking to Conversations via federation!
(0.6.8 did not)

Upstream:

## [0.7.0] - 2021-02-12
### Added
- This file.
- An API reachable through _libpurple_ signals. See `lurch_api.h` for details \ 
and usage.
- Testing setup using _cmocka_ and tests for new modules.
- CI setup running the tests in _appveyor_ and reporting coverage results to \ 
_codecov_.
- The possibility to dynamically link against the submodule libaries. \ 
([#151](https://github.com/gkdr/lurch/pull/151)) (thanks, \ 
[@fortysixandtwo](https://github.com/fortysixandtwo)!)

### Changed
- A new `/command` handler using the API, replacing the old implementation. The \ 
commands are a bit different and some are new.
- Updated _libomemo_ submodule to 0.7.1. See the \ 
[changelog](https://github.com/gkdr/libomemo/blob/master/CHANGELOG.md) for \ 
details.
- Updated _axc_ submodule to 0.3.4. See the \ 
[changelog](https://github.com/gkdr/axc/blob/master/CHANGELOG.md) for details.

### Removed
- The `lurch_initialised` setting in the `accounts.xml`.

### BUGFIXES