[TASK] allow and test PHP 8.5 + drop 8.1 (#22)

Merge pull request #21 from phpsu/php-8.4

Merge pull request #13 from phpsu/feature/add-conditional-arguments

BC: add conditionals for builder and command

Update .travis.yml

Merge branch 'main' of github.com:phpsu/ShellCommandBuilder into main

Merge pull request #11 from phpsu/feature/implement-shell-variables

✨ adding variables to the shellbuilder

Create .gitattributes

Merge pull request #7 from phpsu/feature/add-conditional-expression

Validation for options and conditional expressions

Update README.md