Merge pull request #70 from zchunk/1.2.0

Release zchunk 1.2.0 with the following changes:
 * Now builds for Windows
 * Can set `--uncompressed` flag when creating zchunk files to also store uncompressed digests
 * `zck_read_header` now indicates whether there's a dictionary and what flags are enabled in the zchunk file
 * Minimum meson version required to build zchunk is now 0.53
 * Switched to use GitHub actions for automated testing
 * Added the following automated test environments:
   * `centos-8-stream`
   * `centos-9-stream`
   * `ubuntu-lts`
   * `windows`, both using Mamba and meson-wrap
   * `macos`