chore: add GavinZZ to mergify and github merit badger (aws#28663)

Add GavinZZ to mergify and github merit badger

Closes #<issue number here>.

----

*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: '[rix0rrr,MrArnoldPalmer,iliapolo,otaviomacedo,madeline-k,kaizencc,comcalvi,TheRealAmazonKendra,vinayak-kukreja,mrgrain,pahud,cgarvis,kellertk,HBobertz,sumupitchayan,SankyRed,udaypant,colifran,khushail,scanlonp,mikewrighton,moelasmar,paulhcsun,awsmjs,evgenyka,aws-cdk-automation,dependabot[bot],mergify[bot]]'
+          ignore-usernames: '[rix0rrr,MrArnoldPalmer,iliapolo,otaviomacedo,madeline-k,kaizencc,comcalvi,TheRealAmazonKendra,vinayak-kukreja,mrgrain,pahud,cgarvis,kellertk,HBobertz,sumupitchayan,SankyRed,udaypant,colifran,khushail,scanlonp,mikewrighton,moelasmar,paulhcsun,awsmjs,evgenyka,GavinZZ,aws-cdk-automation,dependabot[bot],mergify[bot]]'

.mergify.yml

@@ -11,7 +11,7 @@ pull_request_rules:
       label:
         add: [ contribution/core ]
     conditions:
-      - author~=^(rix0rrr|MrArnoldPalmer|iliapolo|otaviomacedo|madeline-k|kaizencc|comcalvi|TheRealAmazonKendra|vinayak-kukreja|mrgrain|pahud|cgarvis|kellertk|HBobertz|sumupitchayan|SankyRed|udaypant|colifran|scanlonp|mikewrighton|moelasmar|paulhcsun|awsmjs|evgenyka)$
+      - author~=^(rix0rrr|MrArnoldPalmer|iliapolo|otaviomacedo|madeline-k|kaizencc|comcalvi|TheRealAmazonKendra|vinayak-kukreja|mrgrain|pahud|cgarvis|kellertk|HBobertz|sumupitchayan|SankyRed|udaypant|colifran|scanlonp|mikewrighton|moelasmar|paulhcsun|awsmjs|evgenyka|GavinZZ)$
       - -label~="contribution/core"
   - name: automatic merge
     actions: