Fix title level in README

Fix typo

Try 'gem install --force bundler' on 3.1 Windows

Remove 2.5 from example as it is EOL

Add JRuby 9.2.20.1 and 9.3.2.0

Add 2.6.9, 2.7.5 and 3.0.3 on Windows

Also add 2.6.9 and 2.7.5

Test 3.1 too

Add JRuby 9.2.20.0

Add TruffleRuby and TruffleRuby GraalVM