Fix end in select in some cases was inclusive (#54)

Co-authored-by: Marat Karimov <mkarimov@ourgapps.com>

Author: hazge

memory_partition.go

@@ -233,7 +233,7 @@ func (m *memoryMetric) selectPoints(start, end int64) []*DataPoint {
 		})
 	}
 
-	if end >= maxTimestamp {
+	if end > maxTimestamp {
 		endIdx = int(size)
 	} else {
 		// Use binary search because points are in-order.

memory_partition_test.go

@@ -87,7 +87,7 @@ func Test_memoryPartition_SelectDataPoints(t *testing.T) {
 			name:   "select some points",
 			metric: "metric1",
 			start:  2,
-			end:    4,
+			end:    5,
 			memoryPartition: func() *memoryPartition {
 				m := newMemoryPartition(nil, 0, "").(*memoryPartition)
 				m.insertRows([]Row{
@@ -117,6 +117,7 @@ func Test_memoryPartition_SelectDataPoints(t *testing.T) {
 			want: []*DataPoint{
 				{Timestamp: 2, Value: 0.1},
 				{Timestamp: 3, Value: 0.1},
+				{Timestamp: 4, Value: 0.1},
 			},
 		},
 		{