chore: remove GitHub Actions CI workflow and stale session notes

- Delete .github/workflows/ci.yml and not.md.
- Drop the now-inaccurate "GitHub Actions CI" claims from README/CHANGELOG so
  the v1.1.0 docs match reality (the ezdxf-in-your-CI capability notes remain).

.github/workflows/ci.yml

@@ -1,42 +0,0 @@
-name: CI
-
-on:
-  push:
-    branches: [main, master]
-  pull_request:
-    branches: [main, master]
-
-jobs:
-  lint:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-python@v5
-        with:
-          python-version: "3.11"
-      - run: pip install ruff
-      - run: ruff check .
-      - run: ruff format --check .
-
-  test:
-    runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        python-version: ["3.11", "3.12"]
-    steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-python@v5
-        with:
-          python-version: ${{ matrix.python-version }}
-      - name: Install dependencies
-        run: |
-          pip install -e ".[pdf]"
-          pip install pytest pytest-asyncio pytest-cov ruff
-      - name: Run tests
-        run: pytest --cov=. --cov-report=xml --cov-report=term-missing -v
-      - name: Upload coverage
-        if: matrix.python-version == '3.11'
-        uses: actions/upload-artifact@v4
-        with:
-          name: coverage-report
-          path: coverage.xml