Revert fastavro to non-optional dependency

Currently, skipping the avro extras would lead to an ImportError.

It doesn't really make sense to make fastavro optional in the context of
deserialization, no way to know ahead of time that the messages being
deserialized definitely won't contain Avro schemas.

This could only work if the deserializer had a plan for what to do when
encountering a message serialized with a schema that requires a skipped
dependency (raise an exception? skip the message? call a callback?)

Author: cdebost

README.md

@@ -32,15 +32,14 @@ Clone this repository and install it:
 python setup.py install -e .
 ```
 
-You most likely want to install one or more extras. For example, to use the schema registry with Avro schemas and [kafka-python](https://pypi.org/project/kafka-python/), you should install the `avro` and `kafka-python` extra:
+This library includes opt-in extra dependencies that enable support for certain features. For example, to use the schema registry with [kafka-python](https://pypi.org/project/kafka-python/), you should install the `kafka-python` extra:
 
 ```
-python setup.py install -e .[avro, kafka-python]
+python setup.py install -e .[kafka-python]
 ```
 
 Extra name | Purpose
 :--------- | :------
-avro | Allows using Apache Avro schemas, using `fastavro` as a backend
 kafka-python | Provides adapter classes to plug into `kafka-python`
 
 ## Usage

setup.cfg

@@ -33,15 +33,14 @@ python_requires = >=3.7
 install_requires =
     boto3>=1.18.48
     typing-extensions>=3.10.0.2;python_version<"3.8"
+    fastavro>=1.4.5
 setup_requires =
     setuptools
 
 [options.extras_require]
 dev =
     pytest>=6
     flake8>=3
-avro =
-    fastavro>=1.4.5
 kafka-python =
     kafka-python>=2
 

tox.ini

@@ -10,7 +10,7 @@ python =
 [testenv]
 deps = pytest
 commands =
-    pip install . .[dev] .[avro] .[kafka-python]
+    pip install . .[dev] .[kafka-python]
     python -m pytest --ignore tests/integration
 
 [testenv:flake8]
@@ -20,7 +20,7 @@ commands = flake8
 [testenv:mypy]
 deps = mypy
 commands =
-    pip install . .[dev] .[avro] .[kafka-python]
+    pip install . .[dev] .[kafka-python]
     python -m mypy
 
 [pytest]