Bump version to v0.5.4 and add GitHub Actions workflow

- pkg/version/version
  - Updated version from v0.5.3 to v0.5.4

- .github/workflows/test-and-release.yml
  - Added a new workflow for testing and releasing:
    - Runs tests on `push` for version tags and `pull_request` on `main`
    - Builds binaries for Linux, macOS, and Windows
    - Creates GitHub releases upon valid version tags
    - Uploads release assets

.github/workflows/test-and-release.yml

@@ -0,0 +1,60 @@
+name: Test and Release
+
+on:
+  push:
+    tags:
+      - 'v*.*.*'   # Triggers on tags like v1.2.3
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: 1.22
+      - name: Cache Go modules
+        uses: actions/cache@v4
+        with:
+          path: |
+                ~/.cache/go-build
+                ~/go/pkg/mod
+          key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
+          restore-keys: |
+            ${{ runner.os }}-go-
+      - name: Install dependencies
+        run: go mod download
+      - name: Run tests
+        run: go test -v ./...
+
+  release:
+    if: startsWith(github.ref, 'refs/tags/v')
+    runs-on: ubuntu-latest
+    needs: test
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: 1.22
+      - name: Build binaries
+        run: |
+              mkdir -p dist
+              GOOS=linux GOARCH=amd64 go build -o dist/app-linux-amd64
+              GOOS=darwin GOARCH=amd64 go build -o dist/app-darwin-amd64
+              GOOS=windows GOARCH=amd64 go build -o dist/app-windows-amd64.exe
+      - name: Create Release
+        uses: softprops/action-gh-release@v2
+        with:
+          tag_name: ${{ github.ref_name }}
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      - name: Upload Release Assets
+        uses: softprops/action-gh-release@v2
+        with:
+          files: dist/*
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}