extend to matrix tests

.github/workflows/sepp_tests.yml

@@ -7,6 +7,10 @@ on:
     branches: [ master ]
 
 jobs:
+  strategy:
+    matrix:
+      pyversion: [3.9, 3.10]
+
   python_tests:
     runs-on: ubuntu-latest
 
@@ -24,7 +28,7 @@ jobs:
         # conda CLI
         use-mamba: true
         mamba-version: "*"
-        python-version: "3.9"
+        python-version: "${{ py_version }}"
         environment-file: ci/environment.yml
         auto-activate-base: true
         activate-environment: sepp_ci
@@ -49,6 +53,9 @@ jobs:
         path-to-lcov: "coverage.lcov"
 
   linting:
+    strategy:
+      matrix:
+        pyversion: [3.9, 3.10]
     runs-on: ubuntu-latest
     steps:
     - name: Checkout Repo
@@ -64,7 +71,7 @@ jobs:
         # conda CLI
         use-mamba: true
         mamba-version: "*"
-        python-version: "3.9"
+        python-version: "${{ py_version }}"
         environment-file: ci/env_lint.yml
         auto-activate-base: true
         activate-environment: sepp_lint