Save PR number and base SHA in artifact

As preparation for separate uploading to codecov

.github/workflows/tox.yml

@@ -46,3 +46,23 @@ jobs:
         path: |
           reports/**/*
   
+  upload-pr-number-base-sha:
+    name: Save PR number and base SHA in artifact
+    runs-on: ubuntu-latest
+    if: ${{ github.event.number && always() }}
+    env:
+      PR_NUMBER: ${{ github.event.number }}
+      BASE_SHA: ${{ github.event.pull_request.base.sha }}
+    steps:
+      - name: Make PR number file
+        run: |
+          mkdir -p ./extra
+          echo $PR_NUMBER > ./extra/pr_number
+      - name: Make base SHA file
+        run: |
+          echo $BASE_SHA > ./extra/base_sha
+      - name: Upload PR number file and base SHA file
+        uses: actions/upload-artifact@v4
+        with:
+          name: extra
+          path: extra/