Update CI workflow to use merged requirements.txt

Author: WalkingDevFlag

.github/workflows/ci.yml

@@ -28,15 +28,14 @@ jobs:
       uses: actions/cache@v3
       with:
         path: ~/.cache/pip
-        key: ${{ runner.os }}-pip-${{ hashFiles('**/requirements.txt', '**/requirements-dev.txt') }}
+        key: ${{ runner.os }}-pip-${{ hashFiles('**/requirements.txt') }}
         restore-keys: |
           ${{ runner.os }}-pip-
     
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
         pip install -r requirements.txt
-        pip install -r requirements-dev.txt
     
     - name: Lint with flake8
       run: |