ci: Install Docker 스텝 제거

gitea/runner-images:ubuntu-latest 러너 이미지에 Docker가 이미 포함.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.github/workflows/build.yaml

@@ -27,12 +27,6 @@ jobs:
       id: img-ver
       run: echo "content=$(cat ./version | tr -d '\n')" >> $GITHUB_OUTPUT
 
-    - name: Install Docker // Docker 설치
-      run: |
-        curl -fsSL https://get.docker.com -o get-docker.sh
-        sh get-docker.sh        
-      if: runner.os == 'Linux'
-
     - name: Set up Docker Buildx
       # uses: https://github.com/docker/setup-buildx-action@v1
       uses: docker/setup-buildx-action@v1