Add mdns dependency to CI build command. (Tentative fix 1)

Author: camalolo

.github/workflows/unittest.yml

@@ -18,7 +18,7 @@ jobs:
         with:
           esp_idf_version: v5.5
           target: esp32s3
-          command: GITHUB_ACTIONS="true" idf.py build
+          command: idf.py add-dependency "espressif/mdns^1.8.0" ; GITHUB_ACTIONS="true" idf.py build
           path: 'test-ci'
 
       - name: Run tests