Build release variant for nightly workflow

The `nightly-release` GitHub workflow has been updated to build the `NightlyRelease` variant of the app instead of `NightlyDebug`.

This ensures that the nightly release process generates a release-signed APK, aligning the build type with its purpose.

Author: CreativeCodeCat

.github/workflows/nightly-release.yml

@@ -65,7 +65,7 @@ jobs:
         run: chmod +x gradlew
 
       - name: Build with Gradle
-        run: ./gradlew clean && ./gradlew assembleNightlyDebug
+        run: ./gradlew clean && ./gradlew assembleNightlyRelease
 
       - name: Sign APK - Nightly
         uses: ilharp/sign-android-release@v2.0.0