Introducing dependabot for npm & composer

[melroy89]

• Add dependabot for npm packages, group them together. Two groups one group for @symfony and webpack related packages. And the other groups for all the remaining dev packages.
• Add dependabot for composer. Group together for all composer security updates (either minor or patch releases).

[melroy89]

uhm.. Not sure about this ..

I will look into it

[melroy89]

Works now..