ci: drop unused Python 3.7 Docker file

diff --git a/ci/py37.Dockerfile b/ci/py37.Dockerfile
deleted file mode 100644
index fc8b677..0000000
--- a/ci/py37.Dockerfile
+++ /dev/null
@@ -1,23 +0,0 @@
-# Cache break (modify this line to break cirrus' dockerfile build cache) 1
-
-FROM python:3.7
-
-ENV DEBIAN_FRONTEND=noninteractive
-RUN apt-get update
-RUN apt-get install -y \
-    cython3 \
-    git \
-    libpcsclite-dev \
-    libsdl2-dev \
-    libsdl2-image-dev \
-    libslirp-dev \
-    libudev-dev \
-    libusb-1.0-0-dev \
-    qemu-user-static \
-    swig
-
-RUN pip install poetry flake8
-
-ENV LC_ALL=C.UTF-8
-ENV LANG=C.UTF-8
-ENV LANGUAGE=C.UTF-8
diff --git a/poetry.lock b/poetry.lock
index 88af47e..a11e72c 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -1311,4 +1311,4 @@ qt = ["pyside2"]
 [metadata]
 lock-version = "2.1"
 python-versions = "^3.9,<3.13"
-content-hash = "ffa2aebd594ec1a5db15d7325c7bb26036b593faccf363163379e276bff1c191"
+content-hash = "278dc524a94cc0c503225e4a20f353bd09fa3deaab956e9d559c3795a304ad65"
diff --git a/pyproject.toml b/pyproject.toml
index ab98299..034ae79 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -26,7 +26,6 @@ libusb1 = ">=1.7,<4"
 pyside2 = { version = "^5.14.0", optional = true, python = "<3.10" }
 cbor2 = ">=5.4.6,<5.8"
 pyserial = "^3.5"
-dataclasses = {version = "^0.8", python = ">=3.6,<3.7"}
 semver = "^3.0.1"
 noiseprotocol = "^0.3.1"
 protobuf = "^4.23.3"
diff --git a/setup.py b/setup.py
index 7589240..d6255f6 100644
--- a/setup.py
+++ b/setup.py
@@ -39,8 +39,7 @@ install_requires = \
  'typing-extensions>=4.4,<5.0']
 
 extras_require = \
-{':python_version == "3.6"': ['dataclasses>=0.8,<0.9'],
- 'qt:python_version < "3.10"': ['pyside2>=5.14.0,<6.0.0']}
+{'qt:python_version < "3.10"': ['pyside2>=5.14.0,<6.0.0']}
 
 entry_points = \
 {'console_scripts': ['hwi = hwilib._cli:main', 'hwi-qt = hwilib._gui:main']}