chore: add bots to list of ignore-usernames (#22171)

Dependabot and aws-cdk-automation do not need to be given merit badges. There may be more bots that should be added as well.

Love that this got introduced and I really wanted to get a badge!

----

### All Submissions:

* [x] Have you followed the guidelines in our [Contributing guide?](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md)

### Adding new Unconventional Dependencies:

* [ ] This PR adds new unconventional dependencies following the process described [here](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md/#adding-new-unconventional-dependencies)

### New Features

* [ ] Have you added the new feature to an [integration test](https://github.com/aws/aws-cdk/blob/main/INTEGRATION_TESTS.md)?
	* [ ] Did you use `yarn integ` to deploy the infrastructure and generate the snapshot (i.e. `yarn integ` without `--dry-run`)?

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

.github/workflows/github-merit-badger.yml

@@ -17,4 +17,4 @@ jobs:
           badges: '[beginning-contributor,repeat-contributor,valued-contributor,admired-contributor,star-contributor,distinguished-contributor]'
           thresholds: '[0,3,6,13,25,50]'
           badge-type: 'achievement'
-          ignore-usernames: '[RomainMuller,rix0rrr,Jerry-AWS,MrArnoldPalmer,iliapolo,otaviomacedo,madeline-k,kaizencc,comcalvi,corymhall,peterwoodworth,ryparker,TheRealAmazonKendra,vinayak-kukreja,Naumel,mrgrain]'
+          ignore-usernames: '[RomainMuller,rix0rrr,Jerry-AWS,MrArnoldPalmer,iliapolo,otaviomacedo,madeline-k,kaizencc,comcalvi,corymhall,peterwoodworth,ryparker,TheRealAmazonKendra,vinayak-kukreja,Naumel,mrgrain,aws-cdk-automation,dependabot,mergify]'