fix: avoid docker 5.0.0

Dockerfile

@@ -11,7 +11,6 @@ RUN mkdir /tmp/wheelhouse \
  && cd /tmp/wheelhouse \
  && pip3 install wheel \
  && pip3 wheel --no-cache-dir /tmp/src \
- && rm /tmp/wheelhouse/six*.whl \
  && ls -l /tmp/wheelhouse
 
 FROM alpine:${ALPINE_VERSION}

setup.py

@@ -48,7 +48,7 @@ setup(
     version=versioneer.get_version(),
     install_requires=[
         "chardet",
-        "docker",
+        "docker!=5.0.0",
         "entrypoints",
         "escapism",
         "iso8601",
@@ -57,9 +57,6 @@ setup(
         "requests",
         "ruamel.yaml>=0.15",
         "semver",
-        # six installation is a workaround of https://github.com/docker/docker-py/pull/2844.
-        # When removing this, also remove the "rm /tmp/wheelhouse/six*.whl" line in ./Dockerfile
-        "six",
         "toml",
         "traitlets",
     ],