liquid 5.13.0 on Ruby Gems

What's Changed

Update ruby/setup-ruby to v1.295.0 for ubuntu-24.04 support by @aswamy in #2062
Add TruffleRuby in CI by @eregon in #2038
Skip slow test raising many exceptions on non-CRuby by @eregon in #2066
Reject bare-bracket syntax in strict2 and introduce self keyword by @aswamy in #2060
Add strict2_parse to assign and capture tags by @aswamy in #2065
Add strict2_parse to increment and decrement tags by @aswamy in #2067
Remove "strict2" from bare bracket error message by @aswamy in #2077
Update liquid-spec adapters for missing_features by @ianks in #2079
Prevent SelfDrop context mutation across render boundaries by @karreiro in #2082
Fix SelfDrop equality by @karreiro in #2091
Let environment self shadow SelfDrop by @ianks in #2094
Bump to 5.13.0 by @karreiro in #2103

Full Changelog: v5.12.0...v5.13.0