Whenever the password is updated ensure that the hash algorithm is too (#13966) (#13967)

Backport #13966

`user.HashPassword` may potentially - and in fact now likely does - change
the `passwd_hash_algo` therefore whenever the `passwd` is updated, this
also needs to be updated.

Fix #13832

Thanks @fblaese for the hint

Signed-off-by: Andrew Thornton <art27@cantab.net>

routers/user/setting/account.go

@@ -68,7 +68,7 @@ func AccountPost(ctx *context.Context, form auth.ChangePasswordForm) {
 			return
 		}
 		ctx.User.HashPassword(form.Password)
-		if err := models.UpdateUserCols(ctx.User, "salt", "passwd"); err != nil {
+		if err := models.UpdateUserCols(ctx.User, "salt", "passwd_hash_algo", "passwd"); err != nil {
 			ctx.ServerError("UpdateUser", err)
 			return
 		}