Re-evaluate supported python versions

[kevinkjt2000]

One of the dependencies has dropped support for 3.5 (as mentioned in #104). Time to re-evaluate whether claiming support for python3.5 is worth it or not. May as well add 3.9 to the supported list too. If support is still necessary for 3.5, the dependency will have to be updated or replaced.

[Iapetus-11]

The dependency that I was talking about would only be a dependency for an async way to check the status of a Bedrock Edition server, sorry if I caused any confusion.

[kevinkjt2000]

Still python 3.5 is already past EOL, so I plan to re-evaluate whether or not to support that going forward.

[Iapetus-11]

Also in addition to being able to add async Bedrock Edition support more easily, since the query protocol uses UDP as well (iirc) we would benefit by being able to do that more easily as well.

[Iapetus-11]

I contacted the developer of asyncio-dgram about if there was a specific reason for not supporting 3.5, and they went and added support for Python 3.5. Relevant issue: jsbronder/asyncio-dgram#6

[Egorrko]

Btw dnspython v2.0 requires python => 3.6 and contains async query and resolver
https://dnspython.readthedocs.io/en/latest/async.html
https://pypi.org/project/dnspython/

[Iapetus-11]

If it is decided to remove support for Python 3.5 I'd make a PR with async lookup functions that utilize the async resolver.

[kevinkjt2000]

3.5 is end of life already; long live python >= 3.6
I’ll raise a PR when I get a moment tomorrow to update Travis job and PyPi metadata. Feel free to ditch 3.5 during testing. Speaking of which, I should probably make a script that runs tests for each version in a local script/tool.