Remove mistaken import (#368)

The inclusion of `qsim` in this list must be an old mistake that was
covered up by the fact that until recently, `qsim` was an unrelated
package on PyPI. Only `qsimcirq` is needed here.

Author: mhucka

recirq/qcqmc/extra-requirements.txt

@@ -8,5 +8,4 @@ openfermionpyscf
 pandas
 pfapack
 pyscf>=2.1.0 # For Python 3.10 compatability.
-qsim
 qsimcirq>=0.14.0