Add github workflow to run dex --test

--verbose is now passed to doctest runner.

Add github actions badge for tests..

.github/workflows/test.yml

@@ -0,0 +1,27 @@
+name: test
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: 
+          - "3.10"
+          - "3.11"
+          - "3.12"
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Run tests
+        run: python dex --test --verbose

README.rst

@@ -1,6 +1,10 @@
 dex
 ===
 
+.. image:: /~https://github.com/jceb/dex/actions/workflows/test.yml/badge.svg?branch={{ github.ref }}
+   :target: /~https://github.com/jceb/dex/actions
+   :alt: Test Status
+
 Synopsis
 --------