Remove @angular/core dep from knobs peer.

[igor-dv]

Issue: I don't remember where it was mentioned

What I did

We don't want people to install deps of every supported framework, that's why I remove @angular/core from the peer.

[codecov]

Codecov Report

Merging #2640 into master will not change coverage.
The diff coverage is 0%.

@@           Coverage Diff           @@
##           master    #2640   +/-   ##
=======================================
  Coverage   34.33%   34.33%           
=======================================
  Files         388      388           
  Lines        8682     8682           
  Branches      903      889   -14     
=======================================
  Hits         2981     2981           
- Misses       5082     5109   +27     
+ Partials      619      592   -27

Impacted Files	Coverage Δ
addons/knobs/src/angular/helpers.js	0% <ø> (ø)	⬆️
addons/knobs/src/angular/utils.js	0% <0%> (ø)	⬆️
app/react/src/demo/Welcome.js	64.7% <0%> (ø)	⬆️
addons/knobs/src/components/types/Boolean.js	11.62% <0%> (ø)	⬆️
lib/ui/src/libs/withLifecycleDecorator.js	17.14% <0%> (ø)	⬆️
addons/graphql/src/components/FullScreen/index.js	0% <0%> (ø)	⬆️
.../ui/src/modules/ui/components/addon_panel/index.js	34.78% <0%> (ø)	⬆️
addons/links/src/react/components/link.js	78.78% <0%> (ø)	⬆️
...tions/src/lib/types/function/createFunctionEval.js	77.77% <0%> (ø)	⬆️
lib/ui/src/modules/ui/index.js	0% <0%> (ø)	⬆️
... and 50 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update afc322f...2ce834e. Read the comment docs.