build: Release v9.1.0

[ramu-phanimukla]

Added

- A new `exec` command to send autoprotocol to a test workcell
- isort for automatic import sorting
- Example initial tests for `commands` file using `responses` pattern, starting with
  `submit` and `projects`.
- Deprecation warning for existing `-i` option for `projects` command.
- Binder build cache step
- All API requests will now pass the organization context as a request header

Fixed

- Issue with CodeCov for GitHub action CI
- `-i` option for `projects` command did not output anything to console when called from
  cli.
- Pinned numpy to <=1.19.5 due to an incompatibility issue with numpy 1.20.0 on python 3.7

Updated

- Added new option "--names" to `projects` CLI command. This is meant as a better
  named and more intuitive replacement for the existing `-i` option.
- Returned more explicit error statuses for `projects` and `submit` commands.
- Remove notebooks directory as we break it out into a `separate repository <https://github.com/open-strateos/txpy_jupyter_notebooks>`_
- Plumbed test posargs through to allow local execution of specific test files.
- Autoprotocol dependency to >=7.6.1,<8 for `Instruction` `informatics` attribute

[dzleidig]

LGTM