[versioning] post-release version bump

doc/changelog.markdown

@@ -1,6 +1,9 @@
 Lombok Changelog
 ----------------
 
+### v1.18.21 "Edgy Guinea Pig"
+* There is no edge release at the moment; 1.18.20 is the most recent version.
+
 ### v1.18.20 (April 2nd, 2021)
 * PLATFORM: JDK16 support added. [Issue #2681](https://github.com/rzwitserloot/lombok/issues/2681).
 * PLATFORM: All lombok features updated to act in a sane fashion with JDK16's _record_ feature. In particular, you can annotate record components with `@NonNull` to have lombok add null checks to your compact constructor (which will be created if need be).

src/core/lombok/core/Version.java

@@ -30,9 +30,9 @@ public class Version {
 	// ** CAREFUL ** - this class must always compile with 0 dependencies (it must not refer to any other sources or libraries).
 	// Note: In 'X.Y.Z', if Z is odd, its a snapshot build built from the repository, so many different 0.10.3 versions can exist, for example.
 	// Official builds always end in an even number. (Since 0.10.2).
-	private static final String VERSION = "1.18.20";
-//	private static final String RELEASE_NAME = "Edgy Guinea Pig";
-	private static final String RELEASE_NAME = "Envious Ferret";
+	private static final String VERSION = "1.18.21";
+	private static final String RELEASE_NAME = "Edgy Guinea Pig";
+//	private static final String RELEASE_NAME = "Envious Ferret";
 	
 	// Named version history:
 	//   Angry Butterfly