Disable new S3 checksums for S3Proxy compatibility (#2686)

References aws/aws-cli#9214.

.github/workflows/ci.yml

@@ -137,8 +137,7 @@ jobs:
 
       - name: Install awscli2
         run: |
-          # TODO: pin version to work around https://github.com/gaul/s3proxy/issues/760
-          curl "https://awscli.amazonaws.com/AWSCLIV2-2.22.35.pkg" -o /tmp/AWSCLIV2.pkg
+          curl "https://awscli.amazonaws.com/AWSCLIV2.pkg" -o /tmp/AWSCLIV2.pkg
           sudo installer -pkg /tmp/AWSCLIV2.pkg -target /
 
       - name: Build