Fix reference

- Enhancement: Merge upstream/master (#6), by @localheinz

- Enhancement: Synchronize with ergebnis/php-library-template (#7), by @localheinz
- Fix: Use main as default branch name (#8), by @localheinz
- Enhancement: Synchronize with ergebnis/php-library-template (#9), by @localheinz

- Fix: Reference (#4), by @localheinz

Initial release