fix(deps): use @grpc/grpc-js v0.6.10

[alexander-fenster]

Will be released as next.

[codecov]

Codecov Report

Merging #633 into master will increase coverage by 6.69%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #633      +/-   ##
==========================================
+ Coverage   81.73%   88.42%   +6.69%     
==========================================
  Files          61       65       +4     
  Lines        3964     4139     +175     
  Branches      312      320       +8     
==========================================
+ Hits         3240     3660     +420     
+ Misses        638      387     -251     
- Partials       86       92       +6

Impacted Files	Coverage Δ
tools/prepublish.ts	100% <0%> (ø)
test/system-test/test.clientlibs.ts	91.93% <0%> (ø)
test/system-test/showcase-server.ts	79.41% <0%> (ø)
test/system-test/test.endtoend.ts	94.73% <0%> (ø)
...ixtures/google-gax-packaging-test-app/src/index.js	67.25% <0%> (+67.25%)	⬆️
...-gax-packaging-test-app/src/v1beta1/echo_client.js	89.85% <0%> (+89.85%)	⬆️
...oogle-gax-packaging-test-app/test/gapic-v1beta1.js	95.51% <0%> (+95.51%)	⬆️
...google-gax-packaging-test-app/src/v1beta1/index.js	100% <0%> (+100%)	⬆️

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[bcoe]

@alexander-fenster it looks like there is some additional work being done to squash memory leaks here.

Let's pull this in once that thread reaches a resolution.