Certain versions of boto3 trigger MissingContentLength errors when uploading to S3

After updating my Pulp to 3.74.1, pulp.squeezer.rpm_sync fails with:

An exception occurred during task execution. To see the full traceback, use -vvv. The error was: Exception: Task failed to complete. (failed; An error occurred (MissingContentLength) when calling the UploadPart operation: You must provide the Content-Length HTTP header.)
failed: [127.0.0.1] (item={'name': 'elrepo-kernel-el9-x86_64', 'url': 'https://elrepo.org/linux/kernel/el9/x86_64/', 'gpgkey': 'https://www.elrepo.org/RPM-GPG-KEY-elrepo.org', 'path': 'elrepo/kernel/el9/x86_64'}) => {"ansible_loop_var": "item", "attempts": 3, "changed": false, "item": {"gpgkey": "https://www.elrepo.org/RPM-GPG-KEY-elrepo.org", "name": "elrepo-kernel-el9-x86_64", "path": "elrepo/kernel/el9/x86_64", "url": "https://elrepo.org/linux/kernel/el9/x86_64/"}, "msg": "Task failed to complete. (failed; An error occurred (MissingContentLength) when calling the UploadPart operation: You must provide the Content-Length HTTP header.)"}

An exception occurred during task execution. To see the full traceback, use -vvv. The error was: Exception: Task failed to complete. (failed; An error occurred (MissingContentLength) when calling the PutObject operation: You must provide the Content-Length HTTP header.)
failed: [127.0.0.1] (item={'name': 'fedora-8-epel-x86_64', 'url': 'http://ftp.fau.de/epel/8/Everything/x86_64/', 'gpgkey': 'file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-8', 'path': 'epel/8/x86_64'}) => {"ansible_loop_var": "item", "attempts": 3, "changed": false, "item": {"gpgkey": "file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-8", "name": "fedora-8-epel-x86_64", "path": "epel/8/x86_64", "url": "http://ftp.fau.de/epel/8/Everything/x86_64/"}, "msg": "Task failed to complete. (failed; An error occurred (MissingContentLength) when calling the PutObject operation: You must provide the Content-Length HTTP header.)"}

Package                    Version
-------------------------- ---------------
ansible-compat             25.1.5
ansible-core               2.17.10
pulp-glue                  0.29.3

pulp.squeezer 0.0.17

Start by reproducing pulp.squeezer.rpm_sync with the listed package versions and trace the S3 UploadPart and PutObject requests that raise MissingContentLength. Done means the reported RPM synchronization uploads complete successfully without either error.