ci: speed up pull requests

only run py39 fuse2 ubuntu 22.04 and py314 fuse3 ubuntu 24.04.
there are no binary builds in these matrix entries.

the macOS runners are usually super slow.
testing all pythons and building binaries consumes quite some
resources.
thus, only do that on "push" (e.g. when the PR is merged).

.github/workflows/ci.yml

@@ -45,39 +45,28 @@ jobs:
     needs: lint
     strategy:
       fail-fast: false
-      matrix:
-        include:
-            - os: ubuntu-22.04
-              python-version: '3.9'
-              toxenv: py39-fuse2
-            - os: ubuntu-22.04
-              python-version: '3.10'
-              toxenv: py310-fuse3
-            - os: ubuntu-22.04
-              python-version: '3.11'
-              toxenv: py311-fuse2
-              arch: X64
-            - os: ubuntu-22.04-arm
-              python-version: '3.11'
-              toxenv: py311-fuse2
-              arch: ARM64
-            - os: ubuntu-24.04
-              python-version: '3.12'
-              toxenv: py312-fuse3
-            - os: ubuntu-24.04
-              python-version: '3.13'
-              toxenv: py313-fuse3
-            - os: ubuntu-24.04
-              python-version: '3.14'
-              toxenv: py314-fuse3
-            - os: macos-13
-              python-version: '3.11'
-              toxenv: py311-none  # Note: no FUSE testing due to #6099; see also #6196.
-              arch: X64
-            - os: macos-14
-              python-version: '3.11'
-              toxenv: py311-none  # Note: no FUSE testing due to #6099; see also #6196.
-              arch: ARM64
+      # noinspection YAMLSchemaValidation
+      matrix: >-
+        ${{ fromJSON(
+          github.event_name == 'pull_request' && '{
+            "include": [
+              {"os": "ubuntu-22.04", "python-version": "3.9", "toxenv": "py39-fuse2"},
+              {"os": "ubuntu-24.04", "python-version": "3.14", "toxenv": "py314-fuse3"}
+            ]
+          }' || '{
+            "include": [
+              {"os": "ubuntu-22.04", "python-version": "3.9", "toxenv": "py39-fuse2"},
+              {"os": "ubuntu-22.04", "python-version": "3.10", "toxenv": "py310-fuse3"},
+              {"os": "ubuntu-22.04", "python-version": "3.11", "toxenv": "py311-fuse2", "arch": "X64"},
+              {"os": "ubuntu-22.04-arm", "python-version": "3.11", "toxenv": "py311-fuse2", "arch": "ARM64"},
+              {"os": "ubuntu-24.04", "python-version": "3.12", "toxenv": "py312-fuse3"},
+              {"os": "ubuntu-24.04", "python-version": "3.13", "toxenv": "py313-fuse3"},
+              {"os": "ubuntu-24.04", "python-version": "3.14", "toxenv": "py314-fuse3"},
+              {"os": "macos-13", "python-version": "3.11", "toxenv": "py311-none", "arch": "X64"},
+              {"os": "macos-14", "python-version": "3.11", "toxenv": "py311-none", "arch": "ARM64"}
+            ]
+          }'
+        ) }}
 
     env:
       TOXENV: ${{ matrix.toxenv }}