chore: update release notes (#12377)

CHANGELOG.md

@@ -37,6 +37,12 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ## [Unreleased]
 
+## [v0.45.6](https://github.com/cosmos/cosmos-sdk/releases/tag/v0.45.6) - 2022-06-28
+
+### Improvements
+
+* (simapp) [#12314](https://github.com/cosmos/cosmos-sdk/pull/12314) Increase `DefaultGenTxGas` from `1000000` to `10000000`
+
 ### Bug Fixes
 
 * [\#12317](https://github.com/cosmos/cosmos-sdk/pull/12317) Rename `edit-validator` command's `--moniker` flag to `--new-moniker`

RELEASE_NOTES.md

@@ -1,10 +1,9 @@
-# Cosmos SDK v0.45.5 Release Notes
+# Cosmos SDK v0.45.6 Release Notes
 
-This release introduces a few bug fixes and improvements. Notably, it removes
-the redacted error message, fixes a few bugs in the `types` package, and
-indexing of events for failed txs.
+This release introduces a few bug fixes and improvements.
+Notably, it fixes `GetLastCompleteUpgrade` in `x/upgrade` to properly return the latest upgrade.
 
-See the [Cosmos SDK v0.45.5 Changelog](https://github.com/cosmos/cosmos-sdk/blob/v0.45.5/CHANGELOG.md)
+See the [Cosmos SDK v0.45.6 Changelog](https://github.com/cosmos/cosmos-sdk/blob/v0.45.6/CHANGELOG.md)
 for the exhaustive list of all changes.
 
-**Full Commit History**: https://github.com/cosmos/cosmos-sdk/compare/v0.45.4...v0.45.5
+**Full Commit History**: https://github.com/cosmos/cosmos-sdk/compare/v0.45.5...v0.45.6