Prepare for 0.8.0 release

[kanru]

Fixes #528

[codecov]

Codecov Report

Attention: Patch coverage is 92.45283% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 88.24%. Comparing base (0f92a5e) to head (bcbaa09).

Files	Patch %	Lines
src/dictionary/layered.rs	25.00%	3 Missing ⚠️
src/dictionary/sqlite.rs	95.83%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #531      +/-   ##
==========================================
+ Coverage   88.03%   88.24%   +0.21%     
==========================================
  Files          58       58              
  Lines       13569    13604      +35     
==========================================
+ Hits        11945    12005      +60     
+ Misses       1624     1599      -25     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.