Don't have Dependabot group openai updates (dmvassallo#270)

So Dependabot commands can be issued specific to updates to that
package. Currently we are holding it back <1. See dmvassallo#268 (531bdd8).

Author: EliahKagan

.github/dependabot.yml

@@ -10,6 +10,7 @@ updates:
     groups:
       python-dependencies:
         patterns: ['*']
+        exclude-patterns: ['openai']
 
   - package-ecosystem: github-actions
     directory: '/'