chore: update Go and Actions dependencies (#132)

## Summary
- Update Go dependencies: gitea SDK v0.22.1→v0.23.2, mcp-go v0.42.0→v0.44.0, zap v1.27.0→v1.27.1, go-version v1.7.0→v1.8.0, x/crypto v0.43.0→v0.48.0, x/sys v0.37.0→v0.41.0
- Update Actions: checkout v4→v6, setup-go v5→v6, build-push-action v5→v6, goreleaser-action v6→v7

## Test plan
- [x] `go test ./...` passes
- [x] `make build` succeeds

Reviewed-on: https://gitea.com/gitea/gitea-mcp/pulls/132
Co-authored-by: silverwind <me@silverwind.io>
Co-committed-by: silverwind <me@silverwind.io>

.gitea/workflows/test-pr.yml

@@ -7,8 +7,8 @@ jobs:
   check-and-test:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-go@v5
+      - uses: actions/checkout@v6
+      - uses: actions/setup-go@v6
         with:
           go-version-file: 'go.mod'
       - name: lint