Remove unnecessary check in Database#typecast_value_datetime
Remove unnecessary check in Database#typecast_value_datetime

There's no reason to check the class of objects in
typecast_value_datetime, since there's another check in
Sequel.convert_input_timestamp.  Removing the check from
typecast_value_datetime makes it easier to support additional
input types by overriding Sequel.convert_input_timestamp.

offshore-safety/sequel,beni55/sequel,nju520/sequel,chef/sequel,uhoh-itsmaciek/sequel,dennis-d/custom_sequel,offshore-safety/sequel,t-morgan/sequel,davidbegin/sequel,freshpay/sequel,seeARMS/sequel,reubano/sequel,beni55/sequel,pfarrell/sequel,pfarrell/sequel,mpalmer/sequel,uhoh-itsmaciek/sequel,Marketcircle/sequel,gferguson-gd/sequel,nju520/sequel,mpalmer/sequel,yazshel/sequel,offshore-safety/sequel,nicohvi/sequel,reubano/sequel,nicohvi/sequel,t-morgan/sequel,knut2/sequel,gferguson-gd/sequel,bigfix/sequel,dennis-d/custom_sequel,seeARMS/sequel,davidbegin/sequel,yazshel/sequel,knut2/sequel,freshpay/sequel