Enable dependabot

[mojito317]

PR summary

This could help automate efforts of #20, #14 etc.

PR Checklist

Please make sure that your PR fulfills the following requirements:

• The commit message follows the
  Angular Commit Message Guidelines.
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• New tests
• Build/CI related changes
• Documentation content changes
• Other (please describe)

What is the current behavior?

Now we need to manually update the versions of used libs.

What is the new behavior?

Dependabot will create automatic PRs for this.

Does this PR introduce a breaking change?

• Yes
• No

Other information

[codecov]

Codecov Report

Merging #21 (9c535f7) into master (a941df5) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #21   +/-   ##
=======================================
  Coverage   92.26%   92.26%           
=======================================
  Files           8        8           
  Lines        7042     7042           
=======================================
  Hits         6497     6497           
  Misses        545      545           

---

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 a941df5...9c535f7. Read the comment docs.

[mojito317]

Thanks for the review @emlaver and @ricellis! Now I'm about to merge this.