Bump the Java version to 17 in the workflow file

The error message from the GitHub Actions workflow:
```text
An exception occurred applying plugin request [id: 'com.android.library']
> Failed to apply plugin 'com.android.internal.library'.
   > Android Gradle plugin requires Java 17 to run. You are currently using Java 11.
      Your current JDK is located in /usr/lib/jvm/temurin-11-jdk-amd64
      You can try some of the following options:
       - changing the IDE settings.
       - changing the JAVA_HOME environment variable.
       - changing `org.gradle.java.home` in `gradle.properties`.
```

Author: ShreckYe

.github/workflows/demo-gh-pages.yml

@@ -34,7 +34,7 @@ jobs:
       - name: Set up JDK 11
         uses: actions/setup-java@v4
         with:
-          java-version: "11"
+          java-version: "17"
           distribution: "temurin"
 
       - name: Setup Gradle