7z: Copy f for loop closure (#394)

fix: fix iteration bug

7z.go

@@ -82,6 +82,7 @@ func (z SevenZip) Extract(ctx context.Context, sourceArchive io.Reader, pathsInA
 	skipDirs := skipList{}
 
 	for i, f := range zr.File {
+		f := f // make a copy for the Open closure
 		if err := ctx.Err(); err != nil {
 			return err // honor context cancellation
 		}