[deps] Update boto3 requirement in /images/openwisp_base

Updates the requirements on [boto3](https://github.com/boto/boto3) to permit the latest version.
- [Release notes](https://github.com/boto/boto3/releases)
- [Commits](boto/boto3@1.38.28...1.40.1)

---
updated-dependencies:
- dependency-name: boto3
  dependency-version: 1.40.1
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Federico Capoano <f.capoano@openwisp.io>

Author: dependabot[bot]

images/openwisp_base/requirements.txt

@@ -12,4 +12,4 @@ tldextract~=5.3.0
 # these add support for object storage
 # (eg: Amazon S3, GCS)
 django-storages~=1.14.6
-boto3~=1.38.28
+boto3~=1.40.1