Bump flex to ^1.17, v1.13 - old infrastructure shutdown

[em411]

Q	A
Branch?	master
Bug fix?	yes
New feature?	yes
BC breaks?	no
Deprecations?	yes
Related tickets	-
License	MIT

https://symfony.com/blog/the-old-flex-infrastructure-is-shutting-down

[Zales0123]

The base of this pull-request was changed, you need fetch and reset your local branch
if you want to add new commits to this pull request. Reset before you pull, else commits
may become messed-up.

Unless you added new commits (to this branch) locally that you did not push yet,
execute git fetch origin && git reset "patch-2" to update your local branch.

Feel free to ask for assistance when you get stuck 👍

[Zales0123]

Hello @em411! I've allowed myself to change the PR to base on 1.10 branch and bump the flex constraint to 1.17.1 according to @stloyd comment. Thank you, for your contribution! 🎉

[em411]

Hi @Zales0123, sorry for the delay on my side, I didn't saw the response :)
Thanks for your help!

[lchrusciel]

Thank you Emil! 🎉