workflows: add make sample-conf-check as lint-check

Author: mohamedawnallah

.github/workflows/main.yml

@@ -45,6 +45,9 @@ jobs:
         with:
           go-version: '${{ env.GO_VERSION }}'
 
+      - name: Check default values in sample-btcwallet.conf file
+        run: make sample-conf-check
+
       - name: Check code format
         run: make fmt-check