Try building like sphinx-c-autodoc does

.github/workflows/pages.yml

@@ -10,8 +10,22 @@ jobs:
     - uses: actions/checkout@v3
       with:
         submodules: true
+
+    - name: Cache LLVM and Clang
+      id: cache-llvm
+      uses: actions/cache@v4
+      with:
+        path: llvm/lib/libclang.so*
+        key: llvm-17
+
+    - name: Install LLVM and Clang
+      uses: KyleMayes/install-llvm-action@v1
+      with:
+        version: "17.0"
+        cached: ${{ steps.cache-llvm.outputs.cache-hit }}
 
-    - run: sudo apt-get install -y clang libclang-dev
+    - name: Symlink libclang.so
+      run: sudo ln -s ./llvm/lib/libclang.so /usr/lib/x86_64-linux-gnu/libclang-17.so
 
     - name: Use Python 3.12
       uses: actions/setup-python@v5