chore: follow up for #2510 (#2854)

* follow up for #2510

* Update modules/core/02-client/types/keys.go

Co-authored-by: colin axnér <25233464+colin-axner@users.noreply.github.com>

Co-authored-by: colin axnér <25233464+colin-axner@users.noreply.github.com>

CHANGELOG.md

@@ -133,6 +133,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (modules/core/02-client)[\#1676](https://github.com/cosmos/ibc-go/pull/1676) ClientState must be zeroed out for `UpgradeProposals` to pass validation. This prevents a proposal containing information governance is not actually voting on.
 * (modules/core/keeper) [\#2403](https://github.com/cosmos/ibc-go/pull/2403) Added a function in keeper to cater for blank pointers.
 * (modules/core/keeper) [\#2745](https://github.com/cosmos/ibc-go/pull/2745) Fix request wiring for `UpgradedConsensusState` in core query server.
+* (core/02-client) [\#2510](https://github.com/cosmos/ibc-go/pull/2510) Fix client ID validation regex to conform closer to spec.
 
 ## [v5.1.0](https://github.com/cosmos/ibc-go/releases/tag/v5.1.0) - 2022-11-09
 

modules/core/02-client/types/keys.go

@@ -36,6 +36,8 @@ func FormatClientIdentifier(clientType string, sequence uint64) string {
 // parsing client identifiers. The client identifier must be in the form: `{client-type}-{N}
 // which per the specification only permits ASCII for the {client-type} segment and
 // 1 to 20 digits for the {N} segment.
+// `([\w-]+\w)?` allows for a letter or hyphen, with the {client-type} starting with a letter
+// and ending with a letter, i.e. `letter+(letter|hypen+letter)?`.
 var IsClientIDFormat = regexp.MustCompile(`^\w+([\w-]+\w)?-[0-9]{1,20}$`).MatchString
 
 // IsValidClientID checks if the clientID is valid and can be parsed into the client