Fix lint and test GitHub CI workflows

.github/workflows/lint.yml

@@ -2,7 +2,7 @@ name: Lint
 on: [push, pull_request]
 jobs:
   all:
-    runs-on: ubuntu-latest
+    runs-on: macOS-latest
     steps:
     - uses: hecrj/setup-rust-action@v1
       with:

.github/workflows/test.yml

@@ -17,7 +17,7 @@ jobs:
       run: |
         export DEBIAN_FRONTED=noninteractive
         sudo apt-get -qq update
-        sudo apt-get install -y libxkbcommon-dev
+        sudo apt-get install -y libxkbcommon-dev libgtk-3-dev
     - name: Run tests
       run: |
         cargo test --verbose --workspace