Update 10up/simple-local-avatars requirement from ~2.7.6 to ~2.7.7

Updates the requirements on [10up/simple-local-avatars](https://github.com/10up/simple-local-avatars) to permit the latest version.
- [Release notes](https://github.com/10up/simple-local-avatars/releases)
- [Changelog](https://github.com/10up/simple-local-avatars/blob/develop/CHANGELOG.md)
- [Commits](10up/simple-local-avatars@2.7.6...2.7.7)

---
updated-dependencies:
- dependency-name: 10up/simple-local-avatars
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

composer.json

@@ -17,7 +17,7 @@
  "humanmade/clean-html": "^2.0.0",
  "humanmade/altis-reusable-blocks": "~0.2.4",
  "humanmade/asset-loader": "^0.6.3",
- "10up/simple-local-avatars": "~2.7.6"
+ "10up/simple-local-avatars": "~2.7.7"
  },
  "autoload": {
  "files": [