Release v0.4.0

[DmitryNekrasov]

Add a badge with a Kotlin version.
If I understand correctly, the library version in the Readme will be updated automatically after publishing to maven central.

0.4.0

• Fixed the equality bug in PersistentMap — Added proper node promotion during mutable operations to ensure a consistent internal tree structure #217
• Fixed the bug in PersistentMap equals implementation — Ensured proper node promotion during mutable key removal even when nodes share the same owner #218
• Fixed the ghost element issue in PersistentHashSet — Corrected condition check order to ensure proper recursive element promotion after collision removal #219
• Updated Kotlin to version 2.1.20 and core dependencies #213
• Enabled '-Xjvm-default=disable' explicitly to prevent API dump changes #210

[fzhinkin]

Please also update the changelog file.

And I'm not sure if its worth mentioning all build and infra related changes (other than Kotlin version update and -Xjvm-default=disable) in the changelog and release notes - users don't care about it.

[fzhinkin]

If I understand correctly, the library version in the Readme will be updated automatically after publishing to maven central.

It won't. Only the version in the maven-central badge. Versions in the Using in the projectssection needs to be updated manually.

[fzhinkin]

About the library version: Kotlin update may be considered as a significant change, that requires bumping up the version to 0.4.0 (but we didn't do that for previous Kotlin version updates for this library). @ilya-g WDYT?