DO NOT MERGE: check secrets

.github/workflows/secret.yaml

@@ -0,0 +1,26 @@
+name: Secret checker
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  checker:
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: "Check if PYPI_USERNAME exists"
+        env:
+          USERNAME: ${{ secrets.PYPI_USERNAME }}
+        if: ${{ env.USERNAME == '' }}
+        run: |
+          echo "The secret \"PYPI_USERNAME\" has not been set."
+          echo "Please go to \"settings \> secrets \> actions\" to create it."
+      - name: "Check if PYPI_PASSWORD exists"
+        env:
+          PASSWORD: ${{ secrets.PYPI_PASSWORD }}
+        if: ${{ env.PASSWORD == '' }}
+        run: |
+          echo "The secret \"PYPI_PASSWORD\" has not been set."
+          echo "Please go to \"settings \> secrets \> actions\" to create it."