chore: remove migrations 0.42 and below

CHANGELOG.md

@@ -152,6 +152,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (authz)[\#11060](https://github.com/cosmos/cosmos-sdk/pull/11060) `authz.NewMsgGrant` `expiration` is now a pointer. When `nil` is used then no expiration will be set (grant won't expire).
 * (x/distribution)[\#11457](https://github.com/cosmos/cosmos-sdk/pull/11457) Add amount field to `distr.MsgWithdrawDelegatorRewardResponse` and `distr.MsgWithdrawValidatorCommissionResponse`.
 * (x/auth/middleware) [#11413](https://github.com/cosmos/cosmos-sdk/pull/11413) Refactor tx middleware to be extensible on tx fee logic. Merged `MempoolFeeMiddleware` and `TxPriorityMiddleware` functionalities into `DeductFeeMiddleware`, make the logic extensible using the `TxFeeChecker` option, the current fee logic is preserved by the default `checkTxFeeWithValidatorMinGasPrices` implementation. Change `RejectExtensionOptionsMiddleware` to `NewExtensionOptionsMiddleware` which is extensible with the `ExtensionOptionChecker` option. Unpack the tx extension options `Any`s to interface `TxExtensionOptionI`.
+* (migrations) [#1156](https://github.com/cosmos/cosmos-sdk/pull/11556#issuecomment-1091385011) Remove migration code from 0.42 and below. To use previous migrations, checkout previous versions of the cosmos-sdk. 
 
 ### Client Breaking Changes
 

x/auth/migrations/v040/types.go → x/auth/migrations/legacy/legacy.go

@@ -1,5 +1,6 @@
-package v040
+package legacy
 
 const (
 	ModuleName = "auth"
+	AddrLen    = 20
 )