Use github actions for test matrix

.github/workflows/build.yaml

@@ -0,0 +1,48 @@
+name: build and test
+
+on: [push]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+
+        python-version: [
+          # "3.6",  # TODO: Error: The version '3.6' with architecture 'x64' was not found for Ubuntu 22.04.
+          "3.7",
+          "3.8",
+          "3.9",
+          "3.10",
+          "3.11"
+        ]
+        click-version: [
+          "5.1",
+          "6.7",
+          "7.0",
+          "7.1.2",
+          "8.0.4",
+          "8.1.3",
+        ]
+        exclude:
+          # click 8.1 drops support for py36
+          - python-version: "3.6"
+            click-version: "8.1.3"
+
+
+    steps:
+      - uses: actions/checkout@v3
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v4
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Install package
+        run: |
+          python -m pip install --upgrade pip
+          pip install click==${{ matrix.click-version }}
+          python setup.py install
+      - name: Verify click version
+        run: pip freeze click
+      - name: Run tests
+        run: python -m unittest discover -v

README.md

@@ -10,7 +10,9 @@ Installation
 pip install click-command-tree
 ```
 
-Tested against Python 3.4, 3.5, and 3.6 and click >= 5.0
+This is tested against Python versions 3.7 - 3.11 and (latest major release) click versions
+5.x, 6.x, 7.x, 7.1.x, 8.0.x, and 8.1.x.
+
 
 Example
 -------