docs: add workflow status badges to README

Signed-off-by: Nathan Weinberg <[email protected]>

Author: nathan-weinberg

README.md

@@ -1,5 +1,9 @@
 # Taxonomy Schema
 
+![Lint](https://github.com/instructlab/schema/actions/workflows/lint.yml/badge.svg?branch=main)
+![Tests](https://github.com/instructlab/schema/actions/workflows/test.yml/badge.svg?branch=main)
+![Build](https://github.com/instructlab/schema/actions/workflows/pypi.yml/badge.svg?branch=main)
+
 This Python package defines the JSON schema and a parser for the InstructLab [Taxonomy](https://github.com/instructlab/taxonomy) YAML.
 
 Consumers of this schema can `pip install instructlab-schema`, and use the `instructlab.schema.taxonomy.TaxonomyParser` class to parse and validate `qna.yaml` taxonomy files.