Delete tarball after it has been decompressed (#35)

Saves disk space

Merge pull request #29 from esy/prometheansacrifice/chdir-before-cach…

…e-restore

Fix BSD tar issue on Windows by using newer @actions/cache package

Merge pull request #27 from esy/prometheansacrifice/fix-postinstall

Bug fixes in release-postinstall.js

Merge pull request #24 from esy/prometheansacrifice/improvements

Improvements and bug fixes