Bump react/promise from 2.7.0 to 2.7.1

Bumps [react/promise](https://github.com/reactphp/promise) from 2.7.0 to 2.7.1.
- [Release notes](https://github.com/reactphp/promise/releases)
- [Changelog](https://github.com/reactphp/promise/blob/v2.7.1/CHANGELOG.md)
- [Commits](reactphp/promise@v2.7.0...v2.7.1)

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

Author: dependabot-support

composer.json

@@ -10,7 +10,7 @@
     ],
     "require": {
         "php": "^7.2",
-        "react/promise": "^2.5",
+        "react/promise": "^2.7",
         "wyrihaximus/react-child-process-closure": "^1.0"
     },
     "require-dev": {