chore(deps): add grpc-google-common-protos to the deps bom

[igorbernstein2]

It's not used by this client, but this client uses proto-google-common-protos,
and the hbase adapter uses grpc-google-common-protos. So we will use the deps
bom to align the 2. Ideally we would use google-common-protos-bom, but that doesn't
exists

Fixes #<issue_number_goes_here> (it's a good idea to open an issue first for context and/or discussion)

[codecov]

Codecov Report

Merging #144 into master will decrease coverage by 0.01%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master     #144      +/-   ##
============================================
- Coverage     81.74%   81.72%   -0.02%     
  Complexity      952      952              
============================================
  Files            97       97              
  Lines          5927     5927              
  Branches        327      327              
============================================
- Hits           4845     4844       -1     
- Misses          904      905       +1     
  Partials        178      178

Impacted Files	Coverage Δ	Complexity Δ
...om/google/cloud/bigtable/emulator/v2/Emulator.java	60% <0%> (-0.87%)	14% <0%> (ø)

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