Release 2.7 (pyscf#2407)

* Release 2.7

Patch release 2.6.2

Patch release 2.6.1

Release 2.6

Release 2.5

Release 2.4 (pyscf#1904)

* Release 2.4

* Fix macos pypi wheel

Release 2.3 (pyscf#1786)

* Release 2.3.0

* Update ci jobs

* URL in README

* Drop supports for python-3.6

Release 2.2.1

Release 2.2 (pyscf#1619)

* Fix dimension error for 3c2e integrals

* Update conda build jobs

* Release 2.2.0

Release 2.1.1