fix: add build dependencies for CI

.github/workflows/rust.yml

@@ -13,12 +13,19 @@ jobs:
   build:
 
     runs-on: ubuntu-latest
+    env:
+      LLVM_SYS_160_PREFIX: ${{ runner.temp }}/llvm-16
 
     steps:
     - uses: ConorMacBride/install-package@v1
       with:
         apt: libpango1.0-dev libgtk-4-dev
 
+    - uses: KyleMayes/install-llvm-action@v1
+      with:
+        version: "16.0"
+        directory: $LLVM_SYS_160_PREFIX
+
     - uses: actions/checkout@v3
     - name: Build
       run: cargo build --verbose