Release v0.41.1.

A minor maintenance release.  No functional changes.

- Add ToRequest method to ParsedRequest.
- testutil: use ToRequest instead of plumbing
- channel: put (most) tests in a separate package
- Run gofmt from Go 1.19
- Update module dependencies.

Author: creachadair

README.md

@@ -3,7 +3,7 @@
 [![GoDoc](https://img.shields.io/static/v1?label=godoc&message=reference&color=yellow)](https://pkg.go.dev/github.com/creachadair/jrpc2)
 
 This repository provides a Go module that implements a [JSON-RPC 2.0][spec] client and server.
-There is also a working [example in the Go playground](https://go.dev/play/p/q7S6QEanlEL).
+There is also a working [example in the Go playground](https://go.dev/play/p/Ql00UkGrkmC).
 
 ## Packages