ci: fix coverage upload

At least on my local system, there's no suffix.

Author: gadomski

.github/workflows/tests.yml

@@ -89,13 +89,17 @@ jobs:
       - name: Run Nox
         run: |
           nox --python=${{ matrix.python }}
+      
+      - name: (debug) Find coverage
+        run: find . -iname '*coverage*'
 
       - name: Upload coverage data
         if: always() && matrix.session == 'tests'
         uses: "actions/upload-artifact@v4"
         with:
           name: coverage-data
-          path: ".coverage.*"
+          path: ".coverage*"
+          if-no-files-found: error
 
       - name: Upload documentation
         if: matrix.session == 'docs-build'