chore: Set up cargo-release to update the versions in the changelog

Author: poljar

release.toml

@@ -1,8 +1,11 @@
 owners = ["poljar", "github:matrix-org:rust"]
 
 pre-release-commit-message = "chore: Release matrix-sdk version {{version}}"
-pre-release-replacements = []
-pre-release-hook = ["cargo", "xtask", "release", "changelog"]
+pre-release-replacements = [
+    {file="CHANGELOG.md", search="Unreleased", replace="{{version}}"},
+    {file="CHANGELOG.md", search="ReleaseDate", replace="{{date}}"},
+    {file="CHANGELOG.md", search="<!-- next-header -->", replace="<!-- next-header -->\n\n## [Unreleased] - ReleaseDate", exactly=1},
+]
 
 sign-tag = true
 tag-message = "Release {{crate_name}} version {{version}}"