chore: bump subxt and subxt-signer versions (#1722)

* chore: bump subxt and subxt-signer versions

* chore: update changelog

* test: update v15 metadata and remove v11

* fix: clippy errors

* chore: fmt

* bump zip version

* docs: add removed section in CHANGELOG

* docs: comment about compatibility in the README

* docs: comment about compatibility in the README

---------

Co-authored-by: Alejandro Martinez Andres <11448715+al3mart@users.noreply.github.com>

CHANGELOG.md

@@ -8,6 +8,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 - Updated the toolchain version used by `ink_linting` - [#1616](https://github.com/paritytech/cargo-contract/pull/1616)
+- Bump the version of `subxt` and `subxt-signer` - [#1722](https://github.com/use-ink/cargo-contract/pull/1722)
+
+### Removed
+- Remove support for `V11` metadata [#1722](https://github.com/use-ink/cargo-contract/pull/1722)
 
 ## [4.1.1]