Bump execa from 1.0.0 to 2.0.4

Bumps [execa](https://github.com/sindresorhus/execa) from 1.0.0 to 2.0.4.
- [Release notes](https://github.com/sindresorhus/execa/releases)
- [Commits](sindresorhus/execa@v1.0.0...v2.0.4)

Signed-off-by: dependabot-preview[bot] <[email protected]>

Author: dependabot-preview[bot]

npm-shrinkwrap.json

@@ -123,7 +123,7 @@
 		"eslint": "^5.16.0",
 		"eslint-config-google": "^0.14.0",
 		"eslint-plugin-jsdoc": "^4.8.4",
-		"execa": "^1.0.0",
+		"execa": "^2.0.4",
 		"jsdoc": "^3.6.3",
 		"mock-require": "^3.0.3",
 		"nyc": "^14.1.1",