all: upgrade golangci-lint and formatters (#240)

ir/ir.go

@@ -298,7 +298,7 @@ func (d Datum) Interval() (int, int) {
 	return d.Offset, d.Offset + d.Value.Bytes()
 }
 
-// Overlaps returns true
+// Overlaps returns whether d overlaps with other.
 func (d Datum) Overlaps(other Datum) bool {
 	s, e := d.Interval()
 	so, eo := other.Interval()

ir/ir_test.go

@@ -5,7 +5,6 @@ import (
 	"testing"
 
 	"github.com/mmcloughlin/avo/operand"
-
 	"github.com/mmcloughlin/avo/reg"
 )