chore(deps): update dependency protocolbuffers/protobuf to v28 (#37)

| datasource  | package                  | from  | to    |
| ----------- | ------------------------ | ----- | ----- |
| github-tags | protocolbuffers/protobuf | v27.5 | v28.2 |

Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

protoc-gen-go-grpc/dagger/main.go

@@ -23,7 +23,7 @@ func New(
 	goImage string,
 	// +optional
 	// renovate: datasource=github-tags depName=protocolbuffers/protobuf versioning="regex:^v?(?<major>\\d+)\\.(?<minor>\\d+)$"
-	// +default="27.5"
+	// +default="28.2"
 	protobufVersion string,
 	// +optional
 	// renovate: datasource=go depName=google.golang.org/protobuf/cmd/protoc-gen-go versioning=semver