Blocks: Add used packages to fix tests.

These aren't needed to run the code, because they exist in the `wp` namespace as externals, but they are needed for unit tests, since they don't otherwise exist in that context.

See WordPress/gutenberg#17016 (comment).

public_html/wp-content/mu-plugins/blocks/package.json

@@ -16,13 +16,17 @@
 		"npm": ">=6.0.0"
 	},
 	"dependencies": {
+		"@wordpress/api-fetch": "^3.4.0",
+		"@wordpress/block-editor": "3.0.0",
+		"@wordpress/components": "8.1.0",
+		"@wordpress/core-data": "^2.5.0",
+		"@wordpress/date": "^3.4.0",
+		"@wordpress/element": "2.6.0",
 		"classnames": "2.2.6",
 		"react-select": "3.0.4",
 		"rememo": "3.0.0"
 	},
 	"devDependencies": {
-		"@wordpress/components": "8.1.0",
-		"@wordpress/element": "2.6.0",
 		"@wordpress/eslint-plugin": "^2.3.0",
 		"@wordpress/scripts": "3.4.0",
 		"css-loader": "1.0.1",