ci: add matrix for other OSes

Author: OrKoN

.github/workflows/presubmit.yml

@@ -1,5 +1,3 @@
-name: Check code before submitting
-
 permissions: read-all
 
 on:

.github/workflows/run-tests.yml

@@ -1,5 +1,3 @@
-name: Compile and run unit tests
-
 permissions: read-all
 
 on:
@@ -10,8 +8,15 @@ on:
 
 jobs:
   run-tests:
-    runs-on: ubuntu-latest
-
+    name: Tests on ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os:
+          - ubuntu-latest
+          - windows-latest
+          - macos-latest
     steps:
       - name: Check out repository
         uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0