Bump boto3 from 1.17.30 to 1.17.33

Bumps [boto3](https://github.com/boto/boto3) from 1.17.30 to 1.17.33.
- [Release notes](https://github.com/boto/boto3/releases)
- [Changelog](https://github.com/boto/boto3/blob/develop/CHANGELOG.rst)
- [Commits](boto/boto3@1.17.30...1.17.33)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

requirements.txt

@@ -4,7 +4,7 @@ requests>=2, <3
 fsspec>=0.8, <1
 gcsfs>=0.6.2, <0.7  # newer versions fail tests #97
 s3fs==0.4.2, <0.5.2  # newer versions require Python 3.7+
-boto3==1.17.30
+boto3==1.17.33
 lz4>=3, <4
 zarr>=2.4, <2.7
 tqdm>=4.1, <5