v0.5.0: Debug, filters & last modification date improvments

You can now use any Symfony's ExpressionLanguage expression to filter out your contents from the ContentManager and the debug CLI command.
For the native local filesystem provider, git can now be used to fetch the last modification date of a content if available.

Changelog

[d8ee8cc] feature #100 Use Symfony's ExpressionLanguage component for filters (ogizanagi)
[f340be4] feature #101 Use git last commit date for a file as default last modified date (ogizanagi)

Breaking Changes ⚠️

The LastModifiedProcessor now returns a \DateTimeImmutable.
Use \DateTimeInterface or \DateTimeImmutable on your model objects:

-    public ?\DateTime $lastModified = null;
+    public ?\DateTimeInterface $lastModified = null;