Check line break styles

Running `dos2unix` and check if there are any changes to make sure that
we don't include any files with DOS-style line breaks.

.github/workflows/ci_tests.yaml

@@ -31,14 +31,21 @@ jobs:
           python-version: 3.8
 
       - name: Install packages
-        run: pip install black blackdoc flake8 pylint
+        run: |
+          pip install black blackdoc flake8 pylint
+          sudo apt-get install dos2unix
 
       - name: Formatting check (black and flake8)
         run: make check
 
       - name: Linting (pylint)
         run: make lint
 
+      - name: Line breaks check (dos2unix)
+        run: |
+          dos2unix **/*.py **/*.md
+          if [[ $(git ls-files -m) ]]; then git --no-pager diff HEAD; exit 1; fi
+
   test:
     name: ${{ matrix.os }} - Python ${{ matrix.python-version }}
     runs-on: ${{ matrix.os }}

.github/workflows/format-command.yml

@@ -25,12 +25,15 @@ jobs:
 
       # Install formatting tools
       - name: Install formatting tools
-        run: pip install black blackdoc flake8
+        run: |
+          pip install black blackdoc flake8
+          sudo apt-get install dos2unix
 
       # Run "make format" and commit the change to the PR branch
       - name: Commit to the PR branch if any changes
         run: |
           make format
+          dos2unix **/*.py **/*.md
           if [[ $(git ls-files -m) ]]; then
             git config --global user.name 'actions-bot'
             git config --global user.email '58130806+actions-bot@users.noreply.github.com'