opls_180 missing in NonBondedForces section

[umesh-timalsina]

opls_180 is missing in non-bonded forces section. So, no parameters can be inferred.

[justinGilmer]

https://github.com/mosdef-hub/foyer/blob/e270c8b106a1b87cf0c3b4671f4a95907864f08c/foyer/forcefields/xml/oplsaa.xml#L179

Link to the correct opls_180 and parameters