replace travis with github actions

.github/workflows/test.yml

@@ -0,0 +1,31 @@
+name: Test pypairtree
+
+on: [push, pull_request, workflow_dispatch]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python: [3.7, 3.8, 3.9, 3.10]
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Setup Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python }}
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install tox flake8
+      - name: Lint with flake8
+        run: |
+          # stop the build if there are Python syntax errors or undefined names
+          flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
+          # exit-zero treats all errors as warnings.
+          flake8 pypairtree tests setup.py --count --exit-zero --max-line-length=99 --statistics
+      - name: Run the tests
+        run: |
+            tox

README.md

@@ -1,4 +1,4 @@
-# pypairtree [![Build Status](https://travis-ci.org/unt-libraries/pypairtree.svg?branch=master)](https://travis-ci.org/unt-libraries/pypairtree)
+# pypairtree [![Build Status](https://github.com/unt-libraries/pypairtree/actions/workflows/test.yml/badge.svg?branch=master)](https://github.com/unt-libraries/pypairtree/actions)
 
 pypairtree is a Python implementation of Pairtree for storing objects
 in a filesystem hierarchy that maps object identifiers to two character