Use Ruff and fix all its warnings and errors

.github/workflows/build.yml

@@ -2,9 +2,9 @@
 name: Test code
 on:
   push:
-    branches: [ master ]
+    branches: [master]
   pull_request:
-    branches: [ master ]
+    branches: [master]
   workflow_dispatch:
 
 jobs:
@@ -16,7 +16,7 @@ jobs:
       - uses: actions/setup-python@v4
         with:
           python-version: "3.11"
-          cache: 'poetry'
+          cache: "poetry"
       - run: poetry install
       - run: poetry run pytest
         env:
@@ -41,4 +41,4 @@ jobs:
           context: .
           push: ${{ github.event_name != 'pull_request' }}
           tags: ${{ steps.meta.outputs.tags }}
-          labels: ${{ steps.meta.outputs.labels }}
+          labels: ${{ steps.meta.outputs.labels }}