Smtpdfix

Fixes install issues caused by a newline in short description.

Updates SMTPDFix to support python 3.10

- Overwrites `_trigger_server` to avoid issues with SSL context.

Addresses timeout issues and updates project to a more recent standard.

- Adds SSL handshake timeout with a default value of 5 seconds to shorten the timeout in cases where clients don't support opportunistic encryption, but the server is configured to require it. **This works only with Python 3.7 and later.**
- Increase the default time the server will wait to be ready from one to five seconds (the `aiosmtpd` default at the time the change was implemented) to reduce situations where the server times out.

Significant changes to the way that the fixture is configured and adds the ability to consistently make changes to that configuration at runtime.

+ Changes to the fixture should now be made by changing properties in `smtpd.config` which will cause the fixture to call the `reset()` method.
+ Certificate and Key as PEM formatted files can now be explicitly linked and arbitrarily named..

**Includes Potentially Breaking Changes:**

As of version 0.2.10 smtpdfix uses the standard aiosmtpd VRFY handler that will always return "252 Cannot VRFY user, but will accept message and attempt delivery" if an address is provided or "502 Cannot VRFY {address provided}" if not. Version 0.2.9. and earlier of smptdfix would return a 252 coded response if the username provided was verified and in all other cases a 502 error response.

- Updates requirements to aiosmtpd version 1.3.1 or above.
- `SMPTDFix` can now be initialized without providing a hostname and port which defaults to localhost: 8025.
- Better compatibility with AUTH in aiosmtpd by using `AuthResult` as return from AUTH mechanism handlers and the `Authenticator` for processing.
- Uses default aiosmtpd VRFY handling and responses.
- Adds unofficial support for PyPy3 in response to. [Issue 51](https://github.com/bebleo/smtpdfix/issues/51)
- Adds exception handling to prevent cases where unhandled exceptions cause the fixture to hang. Now returns a 421 error and closes the connection. [Issue 51](https://github.com/bebleo/smtpdfix/issues/51)

Updates requirements for security and fixes the version of aiosmtpd for stability.

+ Now requires cryptography version 3.4.4 in response to security reports
+ Upgrades Aiosmtpd to version 1.3.0 or greater to take advantages of updated `AUTH` handling. Versions of aiosmtpd below 1.3.0 are no longer compatible.