Switch back to sha256 from the std library

The std library now also supports the sha assembly instructions on
ARM64. Thus, sha256-simd no longer provides a performance benefit.

cmd/restic/cmd_stats.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"crypto/sha256"
 	"encoding/json"
 	"fmt"
 	"path/filepath"
@@ -16,7 +17,6 @@ import (
 	"github.com/restic/restic/internal/ui/table"
 	"github.com/restic/restic/internal/walker"
 
-	"github.com/minio/sha256-simd"
 	"github.com/spf13/cobra"
 )