Update NOTICE copyright year (#2249)
Update NOTICE copyright year (#2249)

Update NOTICE copyright year to 2021
paul-rogers/drill,paul-rogers/drill,vdiravka/drill,mapr/incubator-drill,superbstreak/drill,mapr/incubator-drill,paul-rogers/drill,johnnywale/drill,mapr/incubator-drill,mapr/incubator-drill,johnnywale/drill,apache/drill,vdiravka/drill,superbstreak/drill,apache/drill,johnnywale/drill,johnnywale/drill,vvysotskyi/drill,vvysotskyi/drill,apache/drill,apache/drill,mapr/incubator-drill,paul-rogers/drill,apache/drill,vvysotskyi/drill,apache/drill,vvysotskyi/drill,vvysotskyi/drill,vdiravka/drill,superbstreak/drill,vdiravka/drill,superbstreak/drill,superbstreak/drill,mapr/incubator-drill,vdiravka/drill,superbstreak/drill,paul-rogers/drill,vvysotskyi/drill,johnnywale/drill,paul-rogers/drill