Enable JDK 21 builds

Signed-off-by: Ashley <73482956+ascopes@users.noreply.github.com>

.github/workflows/build.yml

@@ -21,11 +21,8 @@ jobs:
       fail-fast: false
       matrix:
         os-name: [ubuntu-22.04]
-        java-version: [11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
+        java-version: [11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21-ea]
         include:
-          # Mockito doesn't yet support Java 21, so let's comment it out for now.
-          # - os-name: ubuntu-22.04
-          #   java-version: 21-ea
 
           # MacOS builds (only check Java 17).
           - os-name: macos-12

README.md

@@ -1,4 +1,4 @@
-![Java 11+](https://img.shields.io/badge/Java-11--20-brown?logo=openjdk)
+![Java 11+](https://img.shields.io/badge/Java-11--21-brown?logo=openjdk)
 [![Build Status](https://github.com/ascopes/java-compiler-testing/actions/workflows/build.yml/badge.svg?branch=main)](https://github.com/ascopes/java-compiler-testing/actions/workflows/build.yml)
 [![Maven Central](https://img.shields.io/maven-central/v/io.github.ascopes.jct/java-compiler-testing)](https://repo1.maven.org/maven2/io/github/ascopes/jct/java-compiler-testing)
 [![Code Coverage](https://codecov.io/gh/ascopes/java-compiler-testing/branch/main/graph/badge.svg?token=VT74BP2742)](https://codecov.io/gh/ascopes/java-compiler-testing)

pom.xml

@@ -141,8 +141,12 @@
 
       Tired compilation is modified to reduce the amount of time the JVM wastes JITing
       code during tests.
+
+      Byte Buddy experimental support enables running ByteBuddy (used by Mockito) in JDK
+      experimental builds.
     -->
     <argLine>
+      -Dnet.bytebuddy.experimental=true
       -Dorg.slf4j.simpleLogger.log=INFO
       -Dorg.slf4j.simpleLogger.log.io.github.ascopes.jct=TRACE
       -Xshare:off