Update vendored gomaasapi

[YujiOshima]

Related #414
Current gomaasapi doesn't have testservice about tag operation.
Added in this commit ( juju/gomaasapi#64 ).

Signed-off-by: Yuji Oshima yuji.oshima0x3fd@gmail.com

[codecov]

Codecov Report

Merging #431 into master will increase coverage by 0.11%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #431      +/-   ##
==========================================
+ Coverage   62.36%   62.47%   +0.11%     
==========================================
  Files          73       73              
  Lines        4506     4506              
==========================================
+ Hits         2810     2815       +5     
+ Misses       1361     1358       -3     
+ Partials      335      333       -2

Impacted Files	Coverage Δ
pkg/manager/manager.go	64.84% <0%> (+1.21%)	✅
pkg/broker/client/sse.go	65.11% <0%> (+3.48%)	✅

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[GordonTheTurtle]

Please sign your commits following these rules:
https://github.com/docker/docker/blob/master/CONTRIBUTING.md#sign-your-work
The easiest way to do this is to amend the last commit:

$ git clone -b "updatemaasapi" git@github.com:YujiOshima/infrakit.git somewhere
$ cd somewhere
$ git rebase -i HEAD~842354128048
editor opens
change each 'pick' to 'edit'
save the file and quit
$ git commit --amend -s --no-edit
$ git rebase --continue # and repeat the amend for each commit
$ git push -f

Amending updates the existing PR. You DO NOT need to open a new one.

[YujiOshima]

@chungers Could you merge this? (Test looks failed at place unrelated with this PR. It may be unstable...)