Fix release approval and validate-deps (typedb#148)

## What is the goal of this PR?

We update release approval and validate-deps to match the latest build updates

Increase version to 0.2.1 (typedb#121)

## What is the goal of this PR?

Bump version number to 0.2.1

Install python3 for the release-validate CI job (typedb#96)

## What is the goal of this PR?

Release validate cannot complete without a command set as `python3`.

## What are the changes implemented in this PR?

Add the `install-python` command to `release-validate`

Install python3 for the release-validate CI job (typedb#96)

## What is the goal of this PR?

Release validate cannot complete without a command set as `python3`.

## What are the changes implemented in this PR?

Add the `install-python` command to `release-validate`

Refactor Classifiers (typedb#64)

We have removed repeated code among the supervised classifiers

Grakn 1.5 migration (typedb#58)

## What is the goal of this PR?

- Update the documentation for KGCN
- Migrate to use Grakn commit 20750ca0a46b4bc252ad81edccdfd8d8b7c46caa and Python grakn-client commit 5459d5d88a30631c5ebdac3a9b0d5ea6f184c8ae

## What are the changes implemented in this PR?

- KGCN README improvements, corrections, fixes including updated diagrams
- CI updates to use Grakn distributions hosted on GCP for unit, integration and end-to-end tests

Increments pre-release version number (typedb#46)

- Updates pre-release version number

Pre release upgrade (typedb#33)

* Upgrading to use Grakn commit 760c46dc1f19d572c2abaa61fc5a16bf4ced4312

* Upgrades kglib to use Grakn commit 760c46dc1f19d572c2abaa61fc5a16bf4ced4312, mostly requiring syntax changes and the temporary lack of limits to query result length

* Minor changes to printing confusion matrices and properly passes attribute label values

* Improves READMEs

* Fix for label_extraction_test