zappa_settings: enable upload overwrite

Enable the upload overwrite feature since we seem to re-uploading
new files over the top of existing ones instead of breaking things
up by version for this deployment.

Change-Id: I5d60551e345363633edfca2b6b108a27ecf84834
diff --git a/zappa_settings.yml b/zappa_settings.yml
index ea8335b..3cc80d9 100644
--- a/zappa_settings.yml
+++ b/zappa_settings.yml
@@ -8,6 +8,7 @@
   domain: publish.trustedfirmware.org
   certificate_arn: arn:aws:acm:us-east-1:987685672616:certificate/888711a3-2023-4c5b-9861-e6713ca56060
   environment_variables:
+    ALLOW_UPLOAD_OVERWRITE: "True"
     S3_BUCKET: trustedfirmware-prod-storage
     S3_REGION: us-east-1
     AUTH_BUCKET: tuxput-trustedfirmware-org