fix(deps): update @grpc/grpc-js to ^0.6.6

[callmehiphop]

Thank you for opening a Pull Request! Before submitting your PR, there are a few things you can do to make sure it goes smoothly:

• Make sure to open an issue as a bug/issue before writing your code! That way we can discuss the change, evaluate designs, and agree on the general idea
• Ensure the tests and linter pass
• Code coverage does not decrease (if any source code was changed)
• Appropriate docs were updated (if necessary)

Fixes #770 🦕

[codecov]

Codecov Report

Merging #772 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #772   +/-   ##
=======================================
  Coverage   96.77%   96.77%           
=======================================
  Files          14       14           
  Lines         869      869           
  Branches      182      182           
=======================================
  Hits          841      841           
  Misses          7        7           
  Partials       21       21

---

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 1294ce2...28fa6ec. Read the comment docs.