Update build.yml

.github/workflows/build.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Install GTK packages
-      run: sudo apt-get install build-essential libgtk2.0-dev
+      run: sudo apt-get install build-essential libgtk-3-0
     - uses: actions/checkout@master
     - name: Cache choosenim
       id: cache-choosenim
@@ -27,4 +27,4 @@ jobs:
         path: ~/.nimble
         key: ${{ runner.os }}-nimble-stable
     - uses: jiro4989/setup-nim-action@v1.0.2
-    - run: nimble build -Y
+    - run: nimble build -Y