New upstream version 5.4.1

.github/CODE_OF_CONDUCT.md

.github/CONTRIBUTING.md

.github/SECURITY.md

.github/workflows/static.yml

.github/workflows/tests.yml

.gitignore

.travis.yml

Makefile

README.md

UPGRADING.md

composer.json

phpstan.src.neon.dist

phpstan.tests.neon.dist

phpunit.xml.dist

psalm-baseline.xml

psalm.xml

src/Dotenv.php

src/Environment/AbstractVariables.php

src/Environment/Adapter/AdapterInterface.php

src/Environment/Adapter/ApacheAdapter.php