raise crate version (#154)

Raise version to 0.21.4 (#151)

Merge pull request #149 from terminusdb/raise_version_to_v0.21.3

Raise version to 0.21.3

Merge pull request #147 from terminusdb/raise_version_to_0.21.2

Raise version 0.21.2

Version 0.21.1

* Added a base layer merge operation
* Fixed decimal to accept scientific notation
* Ensured directory entries are written to disk for new layers

Version 0.21.0

* Cache layers in LRU on save
* Move some backend operations to the layer metadata service
* Improve memory use of squash and layer builders

Raise version to 0.20.1 (#127)

Merge pull request #122 from terminusdb/update_readme

update readme with upgrade instructions

Merge pull request #113 from terminusdb/archive_format

Archive format

Merge pull request #110 from terminusdb/raise_version_to_v0.19.10

Raise version to v0.19.10