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.
- requires-python >=3.10 (napalm-device-types needs it), floor
  napalm-device-types>=4.21.1 (was napalm_device_types>=0.4.0), LICENSE
  file, py.typed, SPDX license string, links to git.netork.io, a dev extra
  with floors.
- README (pyproject named one that did not exist) and CHANGELOG.md.
- mypy strict for the package; napalm_zyxel.zyxel_driver is exempt for now
  (24 errors), recorded in the quality baseline with its two complex
  functions. Coverage floor 68 % (measured 68.97 %).

Closes #8

.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 }}