Use actual bash scripting syntax

When the 'if' condition doesn't match, the GitHub action workflow stops and the pipeline fails, use proper bash syntax to fix it.

Also update the setup-python action to the latest version.

Author: roggif

action.yml

@@ -70,7 +70,7 @@ runs:
   using: "composite"
   steps:
 
-    - uses: "actions/setup-python@v2"
+    - uses: "actions/setup-python@v4"
 
     - name: Update Package Versions
       shell: bash
@@ -82,7 +82,10 @@ runs:
 
     - name: Update Python Versions
       shell: bash
-      run: "[[ \"${{inputs.update_python}}\" == \"true\" ]] && sed -i 's/python_versions:.*/python_versions: [\"3.8\", \"3.9\", \"3.10\", \"3.11\"] /' \"${{ inputs.action_path }}\""
+      run: |
+        if [ "${{inputs.update_python}}" == "true" ]; \
+        then sed -i 's/python_versions:.*/python_versions: [3.8, 3.9, 3.10, 3.11] /' "${{ inputs.action_path }}"; \
+        else echo "Skipping python version update"; fi
 
     - name: "Install Jinja2"
       shell: bash