bump version

chore: update readme

Bump version to 2.6.0 (jpadilla#813)

Co-authored-by: José Padilla <[email protected]>

Bump version to 2.5.0 (jpadilla#801)

Co-authored-by: José Padilla <[email protected]>

chore: update changelog

Bump up version to v2.3.0 (jpadilla#703)

Co-authored-by: José Padilla <[email protected]>

Bump up version to v2.2.0 (jpadilla#697)

Co-authored-by: José Padilla <[email protected]>

Bump up version to v2.1.0 (jpadilla#653)

Bump up version to 2.0.1 (jpadilla#604)

Update requirement on `cryptography` (jpadilla#575)