Update to 1.31. Noteworthy changes:
* Support for zstd compression (if zstd is installed).
* The -K option interacts properly with member names given on the command line.
* Fix handling of file shrinkage during read access when --sparse is used.
Update to 1.30. Noteworthy changes:
* Member names containing '..' components are now skipped when extracting.
* Report erroneous use of position-sensitive options.
* --numeric-owner now affects private headers too.
* Fixed the --delay-directory-restore option
* The --warnings=failed-read option
* The --warnings=none option now suppresses all warnings
* Fix reporting of hardlink mismatches during compare