Fix quote doubling decoding

feat: add `.gitattributes`

PHP 8.3 support

Start testing there...

Throw on bad syntax (#23)

* detect when we've reached the end of input when lexing an unterminated string
* added a mode where we throw exceptions for invalid syntax
* added tests for invalid syntax, in both default and exception mode
* documented `$parser->throw_on_bad_syntax`
* get tests running again on php 8.1 (broken by sebastianbergmann/phpunit#4740)

Show a build bade for Github Actions (#21)

* name the build sensibly
* updated the badge images

Set `null` to `true` for fields that default to `NULL`

more lexer tests