Deprecated spaceless tag since Twig 2.7

[KatharinaSt]

Hi folks,

in my project I get a bunch of info messages regarding the following deprecation:

User Deprecated: The spaceless tag in "BraincraftedBootstrapBundle:Form:bootstrap.html.twig" at line 6 is deprecated since Twig 2.7, use the "spaceless" filter with the "apply" tag instead.

The fix should be easy to make:
Replace
{% spaceless %}...{% endspaceless %}
by
{% apply spaceless %}...{% endapply %}

As this would conflict with the current composer.json I suppose a pull request with this change would crash the dependency structure of this project:
"twig/twig": "~1.12|~2.0@dev"

The spaceless filter has been introduced in Twig 2.7.
https://twig.symfony.com/doc/2.x/filters/spaceless.html

Are there any plans for this project to support such newer library versions in the future or is it just kept for legacy support reasons?