4.2.1

This release is essentially the same as 4.2 and 4.1.1, except that it depends on Tokenproducer 3.0 and later.

Testing has shown that xml-dtd 4.2 works fine with Tokenproducer 3.0, but to avoid any potential annoyances I decided to recompile xml-dtd with Tokenproducer 3.0 and produce a new release, just for caution.

Detail of changes

• Use advanced for loop in DefaultEntityResolver.
• Use diamond operator.
• Compile for --release 8.
• Upgrade to tokenproducer 3.0.
• Upgrade to JUnit 5.10.0.
• Upgrade to actions/checkout@v4.
• Upgrade Gradle wrapper to 8.3.
• changes.sh: add a dot at the end of each item.