build(deps): bump google.golang.org/grpc in /swapserverrpc

Bumps [google.golang.org/grpc](https://github.com/grpc/grpc-go) from 1.53.0 to 1.56.3.
- [Release notes](https://github.com/grpc/grpc-go/releases)
- [Commits](https://github.com/grpc/grpc-go/compare/v1.53.0...v1.56.3)

---
updated-dependencies:
- dependency-name: google.golang.org/grpc
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

swapserverrpc/go.mod

@@ -1,8 +1,8 @@
 module github.com/lightninglabs/loop/swapserverrpc
 
 require (
-	google.golang.org/grpc v1.53.0
-	google.golang.org/protobuf v1.28.1
+	google.golang.org/grpc v1.56.3
+	google.golang.org/protobuf v1.30.0
 )
 
 go 1.16