test: throw on deprecation

[JustinBeckwith]

No description provided.

[stephenplusplus]

Some throwing about grpc.load:

> @google-cloud/vision@0.21.1 system-test C:\Users\sawch\dev\nodejs-vision
> mocha system-test/*.js smoke-test/*.js --timeout 600000

DeprecationWarning: grpc.load: Use the @grpc/proto-loader module with grpc.loadPackageDefinition instead
    at GrpcClient.load (C:\Users\sawch\dev\nodejs-vision\node_modules\google-gax\src\grpc.ts:224:27)
    at new OperationsClientBuilder (C:\Users\sawch\dev\nodejs-vision\node_modules\google-gax\src\operations_client.ts:440:38)
    at new lro (C:\Users\sawch\dev\nodejs-vision\node_modules\google-gax\src\index.ts:58:10)
    at new ImageAnnotatorClient (C:\Users\sawch\dev\nodejs-vision\src\v1\image_annotator_client.js:116:29)
    at Suite.<anonymous> (C:\Users\sawch\dev\nodejs-vision\system-test\vision.js:40:16)
    at Object.create (C:\Users\sawch\dev\nodejs-vision\node_modules\mocha\lib\interfaces\common.js:112:19)
    at context.describe.context.context (C:\Users\sawch\dev\nodejs-vision\node_modules\mocha\lib\interfaces\bdd.js:40:27)
    at Object.<anonymous> (C:\Users\sawch\dev\nodejs-vision\system-test\vision.js:28:1)
    at Module._compile (module.js:652:30)
    at Module._extensions..js (module.js:663:10)
    at Object.extensions..js (C:\Users\sawch\dev\nodejs-vision\node_modules\espower-loader\index.js:47:13)
    at Module.load (module.js:565:32)
    at tryModuleLoad (module.js:505:12)
    at Function.Module._load (module.js:497:3)
    at Module.require (module.js:596:17)
    at require (internal/module.js:11:18)
    at C:\Users\sawch\dev\nodejs-vision\node_modules\mocha\lib\mocha.js:250:27
    at Array.forEach (<anonymous>)
    at Mocha.loadFiles (C:\Users\sawch\dev\nodejs-vision\node_modules\mocha\lib\mocha.js:247:14)
    at Mocha.run (C:\Users\sawch\dev\nodejs-vision\node_modules\mocha\lib\mocha.js:576:10)
    at Object.<anonymous> (C:\Users\sawch\dev\nodejs-vision\node_modules\mocha\bin\_mocha:637:18)
    at Module._compile (module.js:652:30)
    at Object.Module._extensions..js (module.js:663:10)
    at Module.load (module.js:565:32)
    at tryModuleLoad (module.js:505:12)
    at Function.Module._load (module.js:497:3)
    at Function.Module.runMain (module.js:693:10)
    at startup (bootstrap_node.js:191:16)
    at bootstrap_node.js:612:3

[JustinBeckwith]

Looks like another one on grpc and gax :)

[codecov]

Codecov Report

Merging #147 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master   #147   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           2      2           
  Lines          83     83           
=====================================
  Hits           83     83

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