adjust ruby 2.6 and 2.7 specific

Author: hmdros

.github/workflows/main.yml

@@ -21,8 +21,8 @@ jobs:
         run: |
           RUBY_VERSION_STR="${{ matrix.ruby-version }}"
           case "$RUBY_VERSION_STR" in
-            2.6*) BUNDLER_CONSTRAINT=">= 2.4.0, < 2.7.0" ;;
-            2.7*) BUNDLER_CONSTRAINT=">= 2.4.0, < 2.7.0" ;;
+            2.6*) BUNDLER_CONSTRAINT=">= 2.2.0, < 2.4.22" ;;
+            2.7*) BUNDLER_CONSTRAINT="2.4.22" ;;
             3.0)  BUNDLER_CONSTRAINT=">= 2.4.0, < 2.7.2" ;;
             3.1)  BUNDLER_CONSTRAINT=">= 2.4.0, < 2.7.2" ;;
             3.2)  BUNDLER_CONSTRAINT=">= 2.7.2, < 4" ;;