Prefer sh over exec in mspec_node rake task
Prefer sh over exec in mspec_node rake task

`exec` would have been prevented the execution of subsequent tasks.

gausie/opal,c42engineering/opal,c42engineering/opal,jgaskins/opal,catprintlabs/opal,jannishuebl/opal,suyesh/opal,kachick/opal,jannishuebl/opal,Ajedi32/opal,domgetter/opal,wied03/opal,opal/opal,opal/opal,c42engineering/opal,catprintlabs/opal,Mogztter/opal,fazibear/opal,suyesh/opal,gabrielrios/opal,Flikofbluelight747/opal,iliabylich/opal,merongivian/opal,fazibear/opal,merongivian/opal,bbatsov/opal,jgaskins/opal,catprintlabs/opal,Flikofbluelight747/opal,castwide/opal,Ajedi32/opal,merongivian/opal,iliabylich/opal,Mogztter/opal,Ajedi32/opal,gausie/opal,kachick/opal,wied03/opal,jgaskins/opal,opal/opal,suyesh/opal,castwide/opal,bbatsov/opal,jannishuebl/opal,wied03/opal,iliabylich/opal,gabrielrios/opal,Flikofbluelight747/opal,bbatsov/opal,Mogztter/opal,castwide/opal,kachick/opal,opal/opal,domgetter/opal,kachick/opal,gabrielrios/opal,gausie/opal,fazibear/opal,Mogztter/opal