package/ghostscript: security bump to version 9.53.0

package/ghostscript: security bump to version 9.53.0

- Use tar.gz as SHA512SUMS does not contain the hash for tar.xz
- Fix CVE-2020-15900: A memory corruption issue was found in Artifex
  Ghostscript 9.50 and 9.52. Use of a non-standard PostScript operator
  can allow overriding of file access controls. The 'rsearch'
  calculation for the 'post' size resulted in a size that was too large,
  and could underflow to max uint32_t.

https://www.ghostscript.com/doc/9.53.0/News.htm

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>