Fix test cases (10) after DIIS update

[fevangelista]

In between updates in Psi4, ambit, and Forte (PR #290) some new errors appeared in the test cases. Investigate and fix.

• [ ] ACI-12
• [ ] AVAS-6 (this seems a discrepancy between SCF energies. Integrals to blame?)
• [ ] DSRG-MRPT3-9
• [ ] FCI-7 (Wrong value of M_s)
• [ ] FCI-EX-1
• [ ] MRDSRG-LDSRG2-DF-SEQ-4
• [ ] MRDSRG-LDSRG2-QC-1
• [ ] MRDSRG-PT2-4
• [ ] MRDSRG-PT2-3
• [ ] MRDSRG-SPIN-ADAPTED-PT2-4

[JonathonMisiewicz]

I just ran aci-12, and it passes locally. output.txt