ci: setup testing for linux, macos and windows platforms

- fix ci for windows: remove bash if/fi
- exlucde failing test from windows
- enable scheduled tests
- use --use-pep517 for pip install: avoid deprecation message
- exlcude windows-latest and pypy-3.9 since there is a problem with installing (missing zlib.h)

.github/workflows/ci.yml

@@ -1,14 +1,23 @@
 name: tests
 
-on: [push]
+on:
+  push:
+  pull_request:
+  schedule:
+    - cron: '*/15 * * * *'
 
 jobs:
   build:
 
-    runs-on: ubuntu-latest
     strategy:
       matrix:
         python-version: ["3.7", "pypy-3.7", "3.8", "pypy-3.8", "3.9", "pypy-3.9", "3.10", "3.11", "3.x"]
+        platform: [ubuntu-latest, macos-latest, windows-latest]
+        exclude:
+          - platform: windows-latest
+          - python-version: [pypy-3.9]
+
+    runs-on: ${{ matrix.platform }}
 
     steps:
       - uses: actions/checkout@v3
@@ -20,7 +29,7 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           pip install flake8 pytest
-          if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
+          pip install --use-pep517 -r requirements.txt
       - name: Lint with flake8
         run: |
           # stop the build if there are Python syntax errors or undefined names
@@ -28,5 +37,4 @@ jobs:
           # exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
           flake8 . --count --exit-zero --max-complexity=10 --max-line-length=200 --statistics
       - name: Test with pytest
-        run: |
-          pytest
+        run: pytest