New features
[4a1d48b] Add flatpickr as a datepicker (@atierant)
[4dc4256] Update design to use Bootstrap 4 (@atierant)
[4768343] Update the design of the language selector (@javiereguiluz)
[0b3e330] Update the design of the source code modal (@javiereguiluz)
[ee044c7] Use readonly properties (@COil)
[04c1798] Use security roles constants (@COil)
[83f8308] Use final classes (@COil)
Maintenance
[dc7ae36] Update recipes (@fabpot)
[e1468d2] Update the project to Symfony 6.3 (@javiereguiluz)
Bug fixes
[39fb43c] Fix comment typo (@slodplaadmin)