Add GitHub Action to run tests

Test matrix runs on Windows/Mac/Linux, Python 3.8-3.12

.github/workflows/python-package.yml

@@ -0,0 +1,43 @@
+# This workflow will install Python dependencies, run tests and lint with a variety of Python versions
+# For more information see: https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-python
+
+name: Python package
+
+on:
+  push:
+    branches: [ "master" ]
+  pull_request:
+    branches: [ "master" ]
+
+jobs:
+  build:
+
+    strategy:
+      fail-fast: false
+      matrix:
+        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]
+        os: ["ubuntu-latest", "windows-latest", "macos-latest"]
+    runs-on: ${{ matrix.os }}
+
+    steps:
+    - uses: actions/checkout@v4
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v5
+      with:
+        python-version: ${{ matrix.python-version }}
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        python -m pip install -e .
+        python -m pip install pytest pytest-cov numpy
+    - name: Test source code and docs
+      run: |
+        pytest --cov . --cov-report xml
+#    - name: Upload coverage reports to Codecov
+#      uses: codecov/codecov-action@v3
+#      with:
+#        token: ${{ secrets.CODECOV_TOKEN }}
+#        flags: ${{ matrix.python-version }}
+#        files: coverage.xml
+#        fail_ci_if_error: true
+#        verbose: true

.gitignore

@@ -12,3 +12,5 @@ uncertainties.egg-info/
 .cache
 # vim temporary files
 .*.swp
+
+coverage.xml

README.rst

@@ -10,13 +10,11 @@ uncertainties
    :target: https://pepy.tech/project/uncertainties
 .. image:: https://codecov.io/gh/lebigot/uncertainties/branch/master/graph/badge.svg
    :target: https://codecov.io/gh/lebigot/uncertainties/
-.. image:: https://travis-ci.com/lebigot/uncertainties.svg?branch=master
-   :target: https://travis-ci.com/lebigot/uncertainties
-.. image:: https://ci.appveyor.com/api/projects/status/j5238244myqx0a0r?svg=true
-   :target: https://ci.appveyor.com/project/lebigot/uncertainties
+.. image:: https://img.shields.io/github/actions/workflow/status/lmfit/uncertainties/python-package.yml?logo=github%20actions
+   :target: https://github.com/lmfit/uncertainties/blob/main/.github/workflows/python-package.yml
 
 **Call for maintainers**: if you want this project to keep living and are ready to maintain it (pull requests management, issue resolution…), please contact me! I am ready to share my knowledge of the code logic by participating in discussions (notably around pull requests and issues).
-   
+
 This is the ``uncertainties`` Python package, which performs **transparent
 calculations with uncertainties** (aka "error propagation"):