btrfs-tools: upgrade 6.1.2 -> 6.1.3

Changelog:
=========
* fi mkswapfile: fix setting size
* mkfs: check zoned support of libblkid
* check: improve error messages for mismatched references
* other:
   * pass CFLAGS to static build
   * documentation updates

Signed-off-by: Wang Mingyu <wangmy@fujitsu.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>