fix libgtk install.

Author: derspyy

.github/workflows/rust.yml

@@ -42,7 +42,7 @@ jobs:
     - uses: rui314/setup-mold@v1
     - name: Install GTK
       if: ${{ matrix.gtk }}
-      run: sudo apt install libgtk-3-dev --fix-missing
+      run: sudo apt update && sudo apt install libgtk-3-dev
     - name: Build
       run: cargo build --release --verbose
     - name: Upload a Build Artifact