diff --git a/poetry.lock b/poetry.lock
index 487aa948..d10d8579 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -6,14 +6,6 @@ category = "dev"
 optional = false
 python-versions = "*"
 
-[[package]]
-name = "appdirs"
-version = "1.4.4"
-description = "A small Python module for determining appropriate platform-specific dirs, e.g. a \"user data dir\"."
-category = "dev"
-optional = false
-python-versions = "*"
-
 [[package]]
 name = "aspy.refactor-imports"
 version = "2.2.0"
@@ -90,25 +82,26 @@ stevedore = ">=1.20.0"
 
 [[package]]
 name = "black"
-version = "21.7b0"
+version = "21.9b0"
 description = "The uncompromising code formatter."
 category = "dev"
 optional = false
 python-versions = ">=3.6.2"
 
 [package.dependencies]
-appdirs = "*"
 click = ">=7.1.2"
 mypy-extensions = ">=0.4.3"
-pathspec = ">=0.8.1,<1"
+pathspec = ">=0.9.0,<1"
+platformdirs = ">=2"
 regex = ">=2020.1.8"
 tomli = ">=0.2.6,<2.0.0"
 typed-ast = {version = ">=1.4.2", markers = "python_version < \"3.8\""}
-typing-extensions = {version = ">=3.7.4", markers = "python_version < \"3.8\""}
+typing-extensions = ">=3.10.0.0"
 
 [package.extras]
 colorama = ["colorama (>=0.4.3)"]
 d = ["aiohttp (>=3.6.0)", "aiohttp-cors (>=0.4.0)"]
+jupyter = ["ipython (>=7.8.0)", "tokenize-rt (>=3.2.0)"]
 python2 = ["typed-ast (>=1.4.2)"]
 uvloop = ["uvloop (>=0.15.2)"]
 
@@ -1131,17 +1124,13 @@ testing = ["pytest (>=4.6)", "pytest-checkdocs (>=2.4)", "pytest-flake8", "pytes
 [metadata]
 lock-version = "1.1"
 python-versions = ">=3.7.1,<3.10"
-content-hash = "600dccbf9c6ecb15fd6ff2e7efe7154bc2d963756c6dbe2bfe2ad2a5a7bc38dd"
+content-hash = "591503db7460bdd2a40ba162b343f1fe7877494bb1c23934ce60a20e99408445"
 
 [metadata.files]
 alabaster = [
     {file = "alabaster-0.7.12-py2.py3-none-any.whl", hash = "sha256:446438bdcca0e05bd45ea2de1668c1d9b032e1a9154c2c259092d77031ddd359"},
     {file = "alabaster-0.7.12.tar.gz", hash = "sha256:a661d72d58e6ea8a57f7a86e37d86716863ee5e92788398526d58b26a4e4dc02"},
 ]
-appdirs = [
-    {file = "appdirs-1.4.4-py2.py3-none-any.whl", hash = "sha256:a841dacd6b99318a741b166adb07e19ee71a274450e68237b4650ca1055ab128"},
-    {file = "appdirs-1.4.4.tar.gz", hash = "sha256:7d5d0167b2b1ba821647616af46a749d1c653740dd0d2415100fe26e27afdf41"},
-]
 "aspy.refactor-imports" = [
     {file = "aspy.refactor_imports-2.2.0-py2.py3-none-any.whl", hash = "sha256:7a18039d2e8be6b02b4791ce98891deb46b459b575c52ed35ab818c4eaa0c098"},
     {file = "aspy.refactor_imports-2.2.0.tar.gz", hash = "sha256:78ca24122963fd258ebfc4a8dc708d23a18040ee39dca8767675821e84e9ea0a"},
@@ -1167,8 +1156,8 @@ bandit = [
     {file = "bandit-1.7.0.tar.gz", hash = "sha256:8a4c7415254d75df8ff3c3b15cfe9042ecee628a1e40b44c15a98890fbfc2608"},
 ]
 black = [
-    {file = "black-21.7b0-py3-none-any.whl", hash = "sha256:1c7aa6ada8ee864db745b22790a32f94b2795c253a75d6d9b5e439ff10d23116"},
-    {file = "black-21.7b0.tar.gz", hash = "sha256:c8373c6491de9362e39271630b65b964607bc5c79c83783547d76c839b3aa219"},
+    {file = "black-21.9b0-py3-none-any.whl", hash = "sha256:380f1b5da05e5a1429225676655dddb96f5ae8c75bdf91e53d798871b902a115"},
+    {file = "black-21.9b0.tar.gz", hash = "sha256:7de4cfc7eb6b710de325712d40125689101d21d25283eed7e9998722cf10eb91"},
 ]
 cached-property = [
     {file = "cached-property-1.5.2.tar.gz", hash = "sha256:9fa5755838eecbb2d234c3aa390bd80fbd3ac6b6869109bfc1b499f7bd89a130"},
diff --git a/pyproject.toml b/pyproject.toml
index 4a9db26c..6f183f5f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -45,7 +45,7 @@ sphinx = "^4.0.2"
 sphinx-autobuild = "^2021.3.14"
 pre-commit = "^2.14.1"
 flake8 = "^3.9.0"
-black = "^21.7b0"
+black = "^21.9b0"
 flake8-bandit = "^2.1.2"
 flake8-bugbear = "^21.4.3"
 flake8-docstrings = "^1.6.0"