Revert "bump ruby to latest patch"

This reverts commit 4950086.

Author: mgrunberg

.github/workflows/ci.yml

@@ -13,7 +13,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [2.7.5, 3.0.3]
+        ruby: [2.7.3, 3.0.1]
 
     steps:
       - name: Checkout code