Fix wrong Eclipse version in readme

Author: planger

README.md

@@ -51,4 +51,4 @@ The runnable product will be available in `com.eclipsesource.megit.product/targe
 - 0.1.0 Update to Eclipse EGit 2021-12
 - 0.2.0 Update to Eclipse EGit 2022-06
 - 0.3.0 Update to Eclipse EGit 2022-12
-- 0.4.0 Update to Eclipse EGit 2023-12
+- 0.4.0 Update to Eclipse EGit 2023-06