ci: use install dependencies automatically

Author: kou

.github/workflows/test.yaml

@@ -1,4 +1,4 @@
-# Copyright (C) 2021-2024  Sutou Kouhei <kou@clear-code.com>
+# Copyright (C) 2021-2025  Sutou Kouhei <kou@clear-code.com>
 #
 # This library is free software; you can redistribute it and/or
 # modify it under the terms of the GNU Lesser General Public
@@ -26,22 +26,20 @@ jobs:
       fail-fast: false
       matrix:
         ruby-version:
-          - "3.1"
           - "3.2"
           - "3.3"
+          - "3.4"
     timeout-minutes: 10
     steps:
       - uses: actions/checkout@v5
-      - name: Install dependencies
-        run: |
-          sudo apt update
-          sudo apt install -y -V \
-            libgirepository1.0-dev \
-            libwebkit2gtk-4.0-dev \
       - uses: ruby/setup-ruby@v1
         with:
           ruby-version: ${{ matrix.ruby-version }}
-          bundler-cache: true
+      # bundler-cache: true doesn't cache automatically installed
+      # system packages.
+      - name: Install dependencies
+        run:
+          bundle install
       - name: Test
         # TODO: No test
         if: |