docs: add v3.0.0 changelog (backport #1056) (#1057)

docs: add v3.0.0 changelog (#1056)

add v3 changelog

(cherry picked from commit 44ec75f)

Co-authored-by: Marius Poke <marius.poke@posteo.de>

CHANGELOG.md

@@ -4,7 +4,21 @@
 
 Add an entry to the unreleased section whenever merging a PR to main that is not targeted at a specific release. These entries will eventually be included in a release.
 
-## v.2.0.0
+## v3.0.0
+
+Date: June 21st, 2023
+
+Interchain Security v3 uses SDK 0.47 and IBC 7. 
+
+* (deps) [#1019](https://github.com/cosmos/interchain-security/pull/1019) Bump multiple dependencies. 
+  * Bump [cosmos-sdk](https://github.com/cosmos/cosmos-sdk) to [v0.47.3](https://github.com/cosmos/cosmos-sdk/releases/tag/v0.47.3).
+  * Bump [ibc-go](https://github.com/cosmos/ibc-go) to [v7.1.0](https://github.com/cosmos/ibc-go/releases/tag/v7.1.0).
+  * Bump [CometBFT](https://github.com/cometbft/cometbft) to [v0.37.1](https://github.com/cometbft/cometbft/releases/tag/v0.37.1).
+* `[x/ccv/provider]` (fix) [#945](https://github.com/cosmos/interchain-security/issues/945) Refactor `AfterUnbondingInitiated` to not panic when `PutUnbondingOnHold` returns error.
+* `[x/ccv/provider]` (fix) [#977](https://github.com/cosmos/interchain-security/pull/977) Avoids panicking the provider when an unbonding delegation was removed through a `CancelUnbondingDelegation` message.
+* `[x/ccv/democracy]` (feat) [#1019](https://github.com/cosmos/interchain-security/pull/1019) Whitelisting non-legacy params in the "democracy module" require the entire module to be whitelisted. 
+
+## v2.0.0
 
 Date: June 1st, 2023