Move execa to devDependencies

Author: SamVerschueren

package.json

@@ -41,7 +41,6 @@
 	],
 	"dependencies": {
 		"eslint-formatter-pretty": "^1.3.0",
-		"execa": "^2.0.4",
 		"globby": "^9.1.0",
 		"meow": "^5.0.0",
 		"path-exists": "^3.0.0",
@@ -55,6 +54,7 @@
 		"ava": "^1.4.1",
 		"cpy-cli": "^2.0.0",
 		"del-cli": "^1.1.0",
+		"execa": "^3.3.0",
 		"react": "^16.9.0",
 		"rxjs": "^6.5.3",
 		"tslint": "^5.11.0",