use ubuntu clang-format, it is newer

Author: rscohn2

.github/workflows/checks.yml

@@ -14,6 +14,7 @@ jobs:
     - uses: actions/setup-python@v2
     - name: Install prerequisites
       run: |
+        apt install -qq clang-format
         python -m pip install --quiet --upgrade pip
         pip install --quiet -r requirements.txt
     - name: Run checks

requirements.txt

@@ -2,6 +2,5 @@
 #
 # SPDX-License-Identifier: MIT
 
-clang-format
 git+https://github.com/fsfe/reuse-tool.git
 pre-commit