Delete coveralls.yml

We are now using Codecov

.github/workflows/coveralls.yml

@@ -1,25 +0,0 @@
-name: 📊 Check Coverage
-on:
-  push:
-    branches:
-      - master
-      - '*.x'
-    paths-ignore:
-      - 'docs/**'
-      - '*.md'
-      - '*.rst'
-  pull_request:
-    branches:
-      - master
-      - '*.x'
-    paths-ignore:
-      - 'docs/**'
-      - '*.md'
-      - '*.rst'
-jobs:
-  coveralls_finish:
-    # check coverage increase/decrease
-    runs-on: ubuntu-latest
-    steps:
-      - name: Coveralls Finished
-        uses: AndreMiras/coveralls-python-action@develop