fix(deps): update dependency yargs to v16 (#480)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [yargs](https://yargs.js.org/) ([source](https://togithub.com/yargs/yargs)) | dependencies | major | [`^15.0.0` -> `^16.0.0`](https://renovatebot.com/diffs/npm/yargs/15.4.1/16.0.1) |

---

### Release Notes

<details>
<summary>yargs/yargs</summary>

### [`v16.0.1`](https://togithub.com/yargs/yargs/blob/master/CHANGELOG.md#&#8203;1601-httpswwwgithubcomyargsyargscomparev1600v1601-2020-09-09)

[Compare Source](https://togithub.com/yargs/yargs/compare/v16.0.0...v16.0.1)

### [`v16.0.0`](https://togithub.com/yargs/yargs/blob/master/CHANGELOG.md#&#8203;1600-httpswwwgithubcomyargsyargscomparev1542v1600-2020-09-09)

[Compare Source](https://togithub.com/yargs/yargs/compare/v15.4.1...v16.0.0)

##### ⚠ BREAKING CHANGES

-   tweaks to ESM/Deno API surface: now exports yargs function by default; getProcessArgvWithoutBin becomes hideBin; types now exported for Deno.
-   find-up replaced with escalade; export map added (limits importable files in Node >= 12); yarser-parser@19.x.x (new decamelize/camelcase implementation).
-   **usage:** single character aliases are now shown first in help output
-   rebase helper is no longer provided on yargs instance.
-   drop support for EOL Node 8 ([#&#8203;1686](https://togithub.com/yargs/yargs/issues/1686))

##### Features

-   adds strictOptions() ([#&#8203;1738](https://www.github.com/yargs/yargs/issues/1738)) ([b215fba](https://www.github.com/yargs/yargs/commit/b215fba0ed6e124e5aad6cf22c8d5875661c63a3))
-   **helpers:** rebase, Parser, applyExtends now blessed helpers ([#&#8203;1733](https://www.github.com/yargs/yargs/issues/1733)) ([c7debe8](https://www.github.com/yargs/yargs/commit/c7debe8eb1e5bc6ea20b5ed68026c56e5ebec9e1))
-   adds support for ESM and Deno ([#&#8203;1708](https://www.github.com/yargs/yargs/issues/1708)) ([ac6d5d1](https://www.github.com/yargs/yargs/commit/ac6d5d105a75711fe703f6a39dad5181b383d6c6))
-   drop support for EOL Node 8 ([#&#8203;1686](https://www.github.com/yargs/yargs/issues/1686)) ([863937f](https://www.github.com/yargs/yargs/commit/863937f23c3102f804cdea78ee3097e28c7c289f))
-   i18n for ESM and Deno ([#&#8203;1735](https://www.github.com/yargs/yargs/issues/1735)) ([c71783a](https://www.github.com/yargs/yargs/commit/c71783a5a898a0c0e92ac501c939a3ec411ac0c1))
-   tweaks to API surface based on user feedback ([#&#8203;1726](https://www.github.com/yargs/yargs/issues/1726)) ([4151fee](https://www.github.com/yargs/yargs/commit/4151fee4c33a97d26bc40de7e623e5b0eb87e9bb))
-   **usage:** single char aliases first in help ([#&#8203;1574](https://www.github.com/yargs/yargs/issues/1574)) ([a552990](https://www.github.com/yargs/yargs/commit/a552990c120646c2d85a5c9b628e1ce92a68e797))

##### Bug Fixes

-   **yargs:** add missing command(module) signature ([#&#8203;1707](https://www.github.com/yargs/yargs/issues/1707)) ([0f81024](https://www.github.com/yargs/yargs/commit/0f810245494ccf13a35b7786d021b30fc95ecad5)), closes [#&#8203;1704](https://www.github.com/yargs/yargs/issues/1704)

</details>

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samples/package.json

@@ -15,7 +15,7 @@
   },
   "dependencies": {
     "@google-cloud/monitoring": "^2.1.1",
-    "yargs": "^15.0.0"
+    "yargs": "^16.0.0"
   },
   "devDependencies": {
     "chai": "^4.2.0",