Release 2.1.1

Release notes updates

Merge pull request pyscf#1099 from sunqm/update-openblas

Update openblas

Merge pull request pyscf#1078 from yangdatou/fix-scf-rks

fix `scf.RKS(mol, xc="b3lyp")`

Merge pull request pyscf#885 from sunqm/trigger-2.0.0a-ci

Release 2.0.0a

PySCF 1.7.6 release

1.7.6a1

Merge pull request pyscf#723 from sunqm/master

Upgrade integral engine to libcint 4

PySCF 1.7.4 release

PySCF 1.7.3 release