Specify shell for each run statement

.github/actions/run_tests/action.yaml

@@ -5,6 +5,7 @@ runs:
   using: "composite"
   steps:
   - run: git config --global core.autocrlf false
+    shell: bash
 
   - name: Set up Python ${{ matrix.python-version }}
     uses: actions/setup-python@v2
@@ -13,6 +14,7 @@ runs:
 
   - name: Capture full Python version in env
     run: echo "PYTHON_FULL_VERSION=$(python --version)" >> $GITHUB_ENV
+    shell: bash
 
   - name: poetry cache # Change CACHE_STRING secret to bust the cache
     uses: actions/cache@v2
@@ -32,12 +34,14 @@ runs:
       echo '::endgroup::'
 
       echo 'DEPS_INSTALLED=true' >> $GITHUB_ENV
+    shell: bash
 
   - name: Code formatting (Black)
     if: ${{ env.DEPS_INSTALLED == 'true' }}
     run: |
       poetry run black --version
       poetry run black --check --diff .
+    shell: bash
 
   - name: Code Style (flake8)
     if: >
@@ -45,8 +49,10 @@ runs:
     run: |
       poetry run pflake8 --version
       poetry run pflake8 jrnl tests
+    shell: bash
 
   - name: Test with pytest
     if: >
       ${{ env.DEPS_INSTALLED == 'true' }}
     run: poetry run pytest --junitxml=reports/pytest/results.xml
+    shell: bash