Some style and general improvements

Hello,

It wasn't possible to make this PR small, sorry. It fixes a lot of formatting issues; that's why it might seem bloated, but it really isn't.

So, I would like to propose some style and general improvements to the project. For your convenience, I'm going to list them in the same order as the Files changed tab shows:

• fix the .editorconfig PHP files wildcard pattern and apply the rules to all the PHP files (mostly a new line at the end of a file)
• apply the .editoconfig rules to other files (including .yml and .json files)
• update build.yml workflow switch to ubuntu-latest
• update build.yml workflow add support for new PHP (8.2, 8.3) and PHPUnit (10, 11) versions
• update .gitignore add new exclusions (including composer.lock - explanation in the next improvement)
• remove the composer.lock file from the project (it is not recommended to store it in the repo for libraries)
• update README.md update the composer command (composer require is more common)
• update README.md update links (some of the links don't work without the https:// prefix)
• update composer.json move the Tests namespace to the development environment
• update composer.json add a scripts section (it allows running tests through the composer, very convenient)
• fix some inconsistencies in code formatting and indentations

If this PR is too big, I can try to divide it into three smaller ones. @isidore let me please know, if you need any help with this PR.