build(deps): bump github.com/btcsuite/btcd in /proxyd

Bumps [github.com/btcsuite/btcd](https://github.com/btcsuite/btcd) from 0.22.0-beta to 0.23.2.
- [Release notes](https://github.com/btcsuite/btcd/releases)
- [Changelog](https://github.com/btcsuite/btcd/blob/master/CHANGES)
- [Commits](https://github.com/btcsuite/btcd/compare/v0.22.0-beta...v0.23.2)

---
updated-dependencies:
- dependency-name: github.com/btcsuite/btcd
  dependency-type: indirect
...
Signed-off-by: dependabot[bot] <support@github.com>

proxyd/go.mod

@@ -28,7 +28,6 @@ require (
 	github.com/alicebob/gopher-json v0.0.0-20200520072559-a9ecdc9d1d3a // indirect
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/bits-and-blooms/bitset v1.7.0 // indirect
-	github.com/btcsuite/btcd v0.22.0-beta // indirect
 	github.com/btcsuite/btcd/btcec/v2 v2.2.0 // indirect
 	github.com/cespare/xxhash/v2 v2.2.0 // indirect
 	github.com/cockroachdb/errors v1.9.1 // indirect