Install socat as test dependency into github build workflow

.github/workflows/build.yml

@@ -33,8 +33,12 @@ jobs:
       run: |
         python -m pip install --upgrade pip
         pip install setuptools wheel pymodbus
+        sudo apt-get install -y socat
 
     - name: Run tests
       working-directory: ${{github.workspace}}/build
       run: make test
       
+    - name: Show failed test log
+      if: ${{ failure() }}
+      run: cat ${{github.workspace}}/build/Testing/Temporary/LastTest.log