Simplify CI test matrix

Author: dolfinus

.github/workflows/test.yml

@@ -21,7 +21,7 @@ jobs:
     name: Run ${{ matrix.mark}} tests (${{ matrix.python-version }} on ${{ matrix.os }})
     runs-on: ${{ matrix.os }}
     strategy:
-      fail-fast: false
+      fail-fast: true
       matrix:
         include:
         # run all the tests on latest Python version
@@ -32,19 +32,6 @@ jobs:
           - os: ubuntu-22.04
             mark: important
             python-version: '3.7'
-          - os: ubuntu-latest
-            mark: important
-            python-version: 'pypy-3.7'
-          - os: ubuntu-latest
-            mark: important
-            python-version: 'pypy-3.10'
-        # for MacOS and Windows always run only minimal tests
-          - os: macos-latest
-            mark: important
-            python-version: '3.13'
-          - os: windows-latest
-            mark: important
-            python-version: '3.13'
 
     steps:
       - name: Checkout code