Add python 3.7 and Ubuntu 22.04 coverage in tests

Author: Stefano Massaroli

.github/workflows/os-coverage.yml

@@ -9,8 +9,8 @@ jobs:
       max-parallel: 15
 
       matrix:
-        os: [ubuntu-18.04, ubuntu-20.04, macos-latest]
-        python-version: [3.8, 3.9]
+        os: [ubuntu-18.04, ubuntu-20.04, ubuntu-22.04, macos-latest]
+        python-version: [3.7, 3.8, 3.9]
         exclude:
           # temporary exclusion until py3.8 deps work on Windows
           - python-version: 3.7