chore: adopt the NAPALM driver standard

- CI moves to .gitea/workflows/ci.yml and calls the shared driver workflow
  of NAPALM/driver-standard; .github/ is gone.
- license = "Apache-2.0" and a LICENSE file: the package declared no
  license at all. README and CHANGELOG.md, py.typed, links to
  git.netork.io, a dev extra with floors; .venv/ and build output ignored.
- Floors on every dependency: napalm-device-types>=4.21.1 (had none),
  napalm>=4.0 (what napalm-device-types needs) and requests>=2.28.0.
  Without them the lowest CI job resolves napalm 0.10, which does not
  build; the tests pass at exactly these floors.
- mypy strict for the package; napalm_yealink.yealink is exempt for now
  (20 errors), recorded in the quality baseline with get_facts'
  complexity. Coverage floor 42 % (measured 42.61 %).

Closes #4

.gitea/workflows/ci.yml

@@ -0,0 +1,15 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+    tags: ["v*"]
+  pull_request:
+
+jobs:
+  driver:
+    uses: NAPALM/driver-standard/.gitea/workflows/driver.yml@main
+    with:
+      standard-ref: main
+    secrets:
+      PYPI_TOKEN: ${{ secrets.PYPI_TOKEN }}