CI: fixed Android build on Ubuntu-latest by expliciting Gradle version to < 9.x.

.github/workflows/build.yml

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index cc84ae2..3ec0800 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -654,8 +654,12 @@
     name: Build - Android
 
     steps:
-    - uses: actions/checkout@v6
+    - name: Setup Gradle
+      uses: gradle/actions/setup-gradle@v6
+      with:
+        gradle-version: '8.14.5'
 
+    - uses: actions/checkout@v6
     - name: Build example_android_opengl3
       run: |
         cd examples/example_android_opengl3/android