Covalent-awslambda-plugin

Fixed

- Fixed CI workflow
- Updated tests

Added

- Workflow files for release

Tests

- Added basic unit tests for executor

Added

- Added unit tests for the custom executor template.

Fixed

- The executor no longer tries to manipulate the return value of the function if function execution failed.

Changed

- Slight refactor for the Covalent microservices refactor.

Changed

- Fixed package structure, so that the plugin is found by Covalent after installing the plugin.
- Added global variable _EXECUTOR_PLUGIN_DEFAULTS, which is now needed by Covalent.
- Changed global variable executor_plugin_name -> EXECUTOR_PLUGIN_NAME in executors to conform with PEP8.