Added supported for old Python 3.6.

Python 3.6 is the default Python version on Ubuntu 18.04 LTS, which is
still within its five-year support period. Having Python 3.6 support
can therefore be useful.

.github/workflows/report_coverage.yml

@@ -15,7 +15,7 @@ jobs:
       - name: Set up Python.
         uses: actions/setup-python@v4
         with:
-            python-version: "3.7"
+            python-version: "3.10"
 
       - name: Install package.
         run: |

.github/workflows/test_commit.yml

@@ -20,7 +20,7 @@ jobs:
       - name: Set up Python.
         uses: actions/setup-python@v4
         with:
-            python-version: "3.7"
+            python-version: "3.10"
 
       - name: Install package.
         run:  pip install .[test]
@@ -34,7 +34,7 @@ jobs:
 
     strategy:
         matrix:
-            python: ["3.7", "3.8", "3.9", "3.10"]
+            python: ["3.6", "3.7", "3.8", "3.9", "3.10"]
 
     runs-on: ubuntu-latest
 

pyproject.toml

@@ -15,9 +15,13 @@ classifiers = [
     'License :: OSI Approved :: MIT License',
 ]
 readme = 'PyPI.md'
-requires-python = '>=3.7'
-dependencies = ['Flake8<5', 'TOMLi']
 dynamic = ['version', 'description']
+requires-python = '>=3.6'
+dependencies = [
+    'Flake8<5',
+    'TOMLi',
+    'TOMLi<2; python_version < "3.7"',
+]
 
 [project.scripts]
 flake8p = 'flake8p:main'

tests/test_integration.py

@@ -14,7 +14,8 @@
 
 def capture(command, fixture):
     folder  = Path(__file__).parent/'fixtures'/fixture
-    process = run(command, stdout=PIPE, text=True, cwd=folder)
+    process = run(command, stdout=PIPE, universal_newlines=True, cwd=folder)
+    # From Python 3.7 on, use `text=True` instead of `universal newlines`.
     return process.stdout.strip()