* Add a new table issue_index to store the max issue index so that issue could be deleted with no duplicated index
* Fix pull index
* Add tests for concurrent creating issues
* Fix lint
* Fix tests
* Fix postgres test
* Add test for migration v180
* Rename wrong test file name
Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: Lauris BH <lauris@nix.lv>
Lunny Xiao