Bump cluster-tools from 1.38 to 1.39 (#128)

* Bump cluster-tools from 1.38 to 1.39

Bumps [cluster-tools](https://github.com/scalableminds/cluster_tools) from 1.38 to 1.39.
- [Release notes](https://github.com/scalableminds/cluster_tools/releases)
- [Commits](scalableminds/cluster_tools@v1.38...v1.39)

Signed-off-by: dependabot-preview[bot] <[email protected]>

Author: dependabot-preview[bot]

requirements.txt

@@ -6,5 +6,5 @@ pytest
 wkw==0.0.7
 requests
 black
-cluster_tools==1.38
+cluster_tools==1.39
 natsort

setup.py

@@ -11,7 +11,7 @@
         "pillow",
         "pyyaml",
         "wkw",
-        "cluster_tools==1.38",
+        "cluster_tools==1.39",
         "natsort",
     ],
     description="A cubing tool for webKnossos",