Include basic usermods in CI

.github/workflows/build.yml

@@ -32,7 +32,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        environment: ${{ fromJSON(needs.get_default_envs.outputs.environments) }} usermods
+        environment: ${{ fromJSON(needs.get_default_envs.outputs.environments) }}
     steps:
     - uses: actions/checkout@v4
     - name: Set up Node.js
@@ -60,6 +60,7 @@ jobs:
     - name: Add usermods environment
       run: |
         cp -v usermods/platformio_override.usermods.ini platformio_override.ini
+        echo -n "custom_usermods = " >> platformio_override.ini
         find usermods/ -name library.json | xargs dirname | xargs -n 1 basename | xargs echo >> platformio_override.ini
 
     - name: Build firmware