Update requirements file name in linter workflow

Author: paulapreuss

.github/workflows/black_linter.yml

@@ -6,7 +6,7 @@ on:
       - 'README.md'
   pull_request:
     branches: 
-      -main
+      - main
 
 jobs:
   build:
@@ -23,8 +23,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install -r app/requirements/testing.txt
-        pip install -r app/requirements/postgres.txt
+        pip install -r app/requirements/local.txt
     - name: Analysing the code with pylint
       run: |
         black --check .