Remove hyper-h2 patches

[VincentVanlaer]

These patches have been upstreamed in python-hyper/h2@fa8a6346 and python-hyper/h2@96aaef14 and have been released as part of h2 version 3.1.1.

[belm0]

(and no one is complaining about h2 v4.x support, which is another signal that purerpc has few users)

[belm0]

I'm not sure why CI isn't running-- I expect it to run on PR's, even for authors outside of python-trio org.

~Oh, this repo is on travis-ci.org, so it has to migrate to .com, or port to github actions.~

[belm0]

Oh, this repo is on travis-ci.org, so it has to migrate to .com, or port to github actions.

actually, I had already ported to Actions 🤔

https://github.com/python-trio/purerpc/commit/62196dc659008d2c17bfa6d6f46022eeae796100

[belm0]

I really don't know why CI isn't running:

• using loosest workflow permissions
• there was no "approve and run" button, so github wasn't waiting for workflow approval
• .yml config has no branch restrictions

workflow permissions setting:

workflow approval instructions:

[belm0]

https://github.com/python-trio/purerpc/blob/9e96b7d6d5436d4b196c1cece208f907fee9c3a9/.github/workflows/ci.yml#L3

maybe should be on: [ pull_request ]