Add DB update function

[TakaakiFuruse]

On sled update...

thread 'main' panicked at 'should be able to open configured file at "/home/orz/.config/jump-kun/history/db"; Unsupported: This database was created using pagecache version 0.18, but our pagecache version is 0.19. Please perform an upgrade using the sled::Db::export and sled::Db::import methods.', /home/orz/.cargo/registry/src/github.com-1ecc6299db9ec823/pagecache-0.19.0/src/config.rs:202:13
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.

Add some function to update db.