Drop Python 3.7 support

Signed-off-by: Jack Zhang <jack4zhang@gmail.com>

.github/workflows/ci.yml

@@ -14,7 +14,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ['3.7', '3.8', '3.9', '3.10', '3.11']
+        python-version: ['3.8', '3.9', '3.10', '3.11']
 
     steps:
     - uses: actions/checkout@v3

.github/workflows/deploy.yml

@@ -18,7 +18,7 @@ jobs:
     - name: Set up Python
       uses: actions/setup-python@v4
       with:
-        python-version: '3.7'
+        python-version: '3.8'
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip

docs/CONTRIBUTE.md

@@ -20,18 +20,18 @@ Development takes place on GitHub, where the git-flow branch structure is used:
 
 ### Prepare development environment
 It is recommended to use Unix systems. You can use free Oracle Virtualbox and Ubuntu.  
-Setup script for Ubuntu system (python version must be 3.7+):
+Setup script for Ubuntu system (python version must be 3.8+):
 ```bash
-python3.7 -m pip install tox
-python3.7 -m pip install .[tests]
-python3.7 -m pytest -munit
+python3 -m pip install tox
+python3 -m pip install .[tests]
+python3 -m pytest -munit
 
 # install ruby (required for pre-commit)
 sudo apt install ruby
 
 # run pre-commit
-python3.7 -m pre_commit install
-python3.7 -m pre_commit run --all-files
+python3 -m pre_commit install
+python3 -m pre_commit run --all-files
 ```
 
 If you use another system procedure might be different.  

setup.py

@@ -42,7 +42,6 @@
         "License :: OSI Approved :: MIT License",
         "Operating System :: OS Independent",
         "Programming Language :: Python :: 3",
-        "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
         "Programming Language :: Python :: 3.9",
         "Programming Language :: Python :: 3.10",