chore(deps): update dependency ruby to v2.7.8

Author: renovate[bot]

.github/workflows/ios.yml

@@ -35,7 +35,7 @@ jobs:
           node-version: lts/*
       - uses: ruby/setup-ruby@v1
         with:
-          ruby-version: 2.7
+          ruby-version: 2.7.8
           working-directory: example/ios
           bundler-cache: true
       - name: Install dependencies