Add tests for multiple Python3 versions

Author: RoryBarnes

.github/workflows/tests.yml

@@ -1,18 +1,34 @@
 name: tests
 
 on:
+  pull_request:
+    branches: [main]
   push:
 
 jobs:
   tests:
-    name: "Run tests"
+    name: 'Run tests on py${{ matrix.python-version }}'
     runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - python-version: '3.6'
+          - python-version: '3.7'
+          - python-version: '3.8'
+          - python-version: '3.9'
+          - python-version: '3.10'
+          - python-version: '3.11'
+          - python-version: '3.12'
+
     steps:
       - name: Clone vplot repo
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
         with:
           fetch-depth: 0
 
+
+
       - name: Set up Python
         uses: conda-incubator/setup-miniconda@v2
         with: