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.
- napalm-device-types >=4.21.1 from PyPI (the floor was 0.4.0).
- LICENSE, CHANGELOG, py.typed, SPDX license string, setuptools>=77,
  version floors on the dev extra (black is gone), links to git.netork.io;
  the README names Python 3.10 and the Gitea CI.
- mypy strict for the package; napalm_fritzbox.fritzbox is exempt for now
  (6 errors), recorded in the quality baseline with four long getters.
- Coverage floor 81 % (measured 81.36 %).

.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 }}