Update "Github Actions" workflows.

Author: KelSolaar

.github/workflows/continuous-integration-static-type-checking.yml

@@ -21,11 +21,6 @@ jobs:
       uses: actions/setup-python@v1
       with:
         python-version: ${{ matrix.python-version }}
-    - name: Install Dependencies (macOS)
-      run: |
-        brew install gnu-sed graphviz
-        ln -s /usr/local/bin/gsed /usr/local/bin/sed
-      shell: bash
     - name: Static Type Checking
       run: |
         pip install -r requirements.txt