exif: Allow more spacing characters in strings

The root cause of issue #8079 was a non-breaking space (U+0160).
`unicode.IsPrint` only allows the ASCII space (U+0020).  Be more lenient
by using `unicode.IsGraphic` instead.

Fixes #8079

resources/images/exif/exif.go

@@ -227,7 +227,7 @@ func (e *exifWalker) Walk(f _exif.FieldName, tag *tiff.Tag) error {
 func nullString(in []byte) string {
 	var rv bytes.Buffer
 	for _, b := range in {
-		if unicode.IsPrint(rune(b)) {
+		if unicode.IsGraphic(rune(b)) {
 			rv.WriteByte(b)
 		}
 	}